Housing & Stocking Levels

Step 1: Finding an APPROPRIATE Home 

Published July 13, 2015

One of the most important aspects to goldfish keeping is the living space you provide. When the proper housing and stocking levels are not met, a domino effect takes control leading to an unhealthy environment. Not giving your goldfish ample swimming room and over-crowding can result in excess waste, improper filtration, and rampant disease. Understanding stocking levels and how much space is required for a comfortable life is just the first lesson in goldfish keeping. 

What are the recommended stocking levels?

Housing and stocking levels are dependent on the current size of the goldfish and their growth rate. In pristine conditions, fancy goldfish tend to grow the most in their first two years of life with a growth rate of about ranging from 0.25 - 1.5 inches per month. The main factors that determine their growth rate is the frequency and amount they are fed, and the water temperature. Goldfish fed a diet high in protein, they generally will grow faster than normal. In a heated aquarium they will reach their maximum size more quickly and could possibly grow beyond their max. But, the catch here is that a higher temperature leads to a shorter life expectancy. Regardless of what type of diet you're feeding and the water temperature, you should stock and house your goldfish with their maximum size in mind (fancy goldfish are generally 6” to 10” long). Don't worry too much about the diet and water temperature right now, we're going to get to that later.

Once people have one, they usually want more. Just remember that healthy goldfish lead to happy keepers, so don’t exceed the recommended stocking levels. During my research, I have learned two methods for stocking. The first has a minimum stocking level of 2.5 gallons (9.5 L) of swimmable space per 1” (2.5 cm) of body length. Swimmable space is the volume of water that is not taken up by substrate, decorations, plants, and internal equipment. The second, and more popular option, is a general recommendation of 15 - 20 gallons (56.9 - 75.7 L) of swimmable space for each double-tailed goldfish and 30 - 40 gallons (113.5 - 151.4 L) for single tails. The first method involving length as a limiting factor can be less accurate because goldfish have a tendency to be different shapes and sizes when fully grown. The second method is more often used because it already assumes maximum length and girth of a goldfish. As with everything, it is all about personal opinion. If you are providing 20 gallons/goldfish and it looks too tight, then it probably is. Sometimes rules needs to be broken to provide the fish with a healthy environment. Be honest with yourself and trust your decisions. If you feel like your fish would do better or have less stress in an "understocked" aquarium, go for it. 

To determine the amount of gallons you need to house your goldies use the equations below:

First you want to determine the size of your tank (if you know how many gallons or liters your tank is, you can skip this step):

Volume (gal or L) = height X width X length (in or cm)

If you have an aquarium with decorations, plants, large rocks/driftwood, or internal equipment calculate the water displaced by these objects and subtract it from the total volume of the tank.

A perfect example of an aquarium that is too tall and overstocked. 

Using the first method, you want to determine the tank volume you need for ample swimming room. Make sure to consider the maximum length of the fish if you don't want to deal with upgrading the aquarium space later down the road. 

Minimum Tank Size = Total Body Length X 2.5 gallons or 9.5 L 

Using the second method, use the following calculation. 

Minimum Tank Size = 15 - 20 gallons X Total Number of Goldfish

What type of housing should I provide?

The type of housing is less important than you might think. Goldfish can really be kept in anything, from the typical tank to a Sterilite container or even a lined apple crate. What I've found is most important when providing the five-walled container is it's shape in regards to length and height.  

It is best to have a tank that is more shallow and long than deep and narrow. I’ve noticed that goldfish tend to swim vertically rather than horizontal. A higher depth of the tank can also cause problems with goldfish due to their predisposition swim bladder issues. Depth and pressure are proportionate, so when one increases so does the other. I’ll try not to bore you with the physics. Basically, the pressure in the tank is the weight of its volume divided by the area in which it sits. If the tank’s area is small and the depth is high, there is increased pressure at the bottom of the tank. The comfort level is around 6” to 18” depending on the size and shape of the goldfish. If you are looking for a container with a greater depth just make sure that the area the container sits on is large to displace the pressure. More rotund goldfish, like the Pearlscale, would do better with a lower depth while more streamlined goldfish, like the Comet, would be more accepting with a greater depth. 

Where should I put my new aquarium?

Location, Location, LOCATION!!! I can not stress enough that the location of your tank can impact your goldfish. Placing an aquarium in high traffic areas can be very stressful for your fish and can lead to hiding when unknown people approach the tank. Large pets may be of concern too since  they could damage or knock over a tank by jumping on it. Make sure to also share with children (and uninformed adults) that they should not tap on the glass. Goldfish do not have the traditional eardrums that we might think, instead they “feel” vibrations from sound. Water being an excellent sound carrier, tapping or even loud speakers can cause excessive vibrations that can startle and stress out your goldfish. 

The placement of your aquarium in relation to your floor joist is extremely important, too. When placing your tank on a non-concrete floor, make sure that the tank is perpendicular to the floor joist. This allow for the full weight of the tank to be supported at multiple points. Keep in mind that the weight of one gallon of water is 8.35 pounds (or, 1L equals 1 kg). Multiple gallons of water, equipment, and decorations can be extremely heavy. In order for the floor to hold, the weight needs to be equally distributed over the joist. I don’t know about you, but coming home to find the tank crashed through the floor and possibly being in the living room of the downstairs neighbor is not an idea of fun. 

I’m sure your fish will appreciate you following these recommendations for goldfish housing and stocking levels. Most of all, remember that we are Goldfish keepers Observing, Learning, and Developing Ideal Environments. Keep your eyes open, always be willing to learn from others and yourself to create a great atmosphere for your goldfish. 

Happy Goldfish Keeping!
- Nikita


Emma. Koko's Goldfish. Keeping Goldfish: A BREIF GUIDE FOR NEW OWNERS. Retrieved June 10, 2015.

Lynx, Jennifer. Solid Goldfish. Goldfish 101. Retrieved June 11, 2015.

Lynx, Jennifer. Solid Goldfish. Goldfish Care Basics: Tank Size. Retrieved June 11, 2015.

Lynx, Jennifer. Solid Goldfish. HOW TO SET UP A GOLDFISH TANK. Retrieved June 11, 2015.

Sharon (shakaho). Koko's Goldfish Forum. Kokos Goldfish Forum Guidelines for Healthy Goldfish. Retrieved June 10, 2015.

Rand, Brenda. Goldfish Emergency. 10 Easy Steps to Goldfish and Koi Keeping. Retrieved June 10, 2015. 

The Goldfish Tank. Goldfish Care: How to take care of goldfish. Retrieved June 10, 2015

Von G, Lynda;  Wellman, Shannon. Koko's Goldfish Ten Step to Healthy Goldfish. Retrieved June 10, 2015. 


Freshwater Source & Treatment

Step 2: The Basis of Water Quality

Published July 20, 2015

Determining the type pf freshwater source and its necessary treatment is one of most important aspects to goldfish keeping. After all, fish do live in water! Providing the right water parameters is key to a goldfish’s health and longevity. When treating the freshwater source we are looking to replenish essential minerals lost over time and remove toxic chemicals that exist at the water source. Whether you have well or tap water, you should easily be able to tweak the water to best suit your goldfish's needs. 

Understanding Your Water's Hardness and Mineral Content

There are three main types of water sources typically use in the aquarium hobby: 

  1. Municipal Water/Tap Water
  2. Well Water
  3. RO/DI Water (reverse osmosis/de-ionized)

With all water sources being different, it is important that you understand your water and its total hardness. Depending on how hard or soft your water source is determines what treatments should be done to ready the water for goldfish. Total hardness is made of two parts, general hardness and carbonate hardness. General hardness is the concentration of calcium and magnesium ions in a volume of water. The degree of hardness is directly proportionate to the amount of minerals in your water source that are needed to support good health in aquariums. Carbonate hardness is the alkalinity of water caused by the presence of carbonate and bicarbonate. These anions have the ability to neutralize acid during naturally occurring pH swings. With good buffering capability, carbonate hardness reduces these stressful swings in pH that can harm your goldfish. Goldfish tend to like moderately hard water with a dGH and dKH around 150. 

If you have soft or very hard water, don't fret, you can have goldfish too. For very hard water you should dilute your water source with RO/DI water. Because RO/DI water does not contain minerals it can be used to decrease the levels of hardness. With soft water, the ions that make up total hardness need to be added to the water to bring up the levels of hardness. Magnesium and calcium in the form of a water additive, like Seachem Replenish, is needed to increase the general hardness. Sodium bicarbonate (known as baking soda) is generally used to increase the carbonate hardness. 

Why are Chlorine and Chloramines added to Tap Water?

If you are planning on using tap water to keep your goldfish, you must use a dechlorinator chemical to protect your fish from the chlorine and chloramines added during municipal water treatments for sanitation purposes. While chlorine and chloramines are safe in small concentrations for humans, these toxins can be deadly to your goldfish. It is important for us to understand that chlorine is not just a nuisance to fishkeepers, but it keeps our drinking water safe for consumption. Understanding how chlorines are used as disinfectants will help us battle them and their by-products to create an idealistic environment for our goldfish.

When compressed, liquid chlorine gas is added to water is readily disolves and hydrolyzes to form hypochlorous acid (HOCl), the disinfectant.

Cl2 + H2O HOCl + H+ + Cl-

Depending on the pH and temperature, hypochlorous acid (HOCl) dissociates to produce a hypochlorite ion (OCl-). A a higher pH, this reaction will happen readily because there are not many hydrogen ions inhibiting the ionization. However, at a lower pH, this reaction can stall because it cannot readily give up its hydrogen atom. A higher temperature would give this reaction energy to move forward and produce more ions. 

HOCl H+ + ClO-

Hypochlorous acid and hypochlorite ions are called free available chlorine (FAC). Chlorine also react with reducing agents, like ammonia, to form chloramines that make the  combined available chlorine (CAC). These reactions are dependent on the concentration of reducing agents, temperature, and pH. 

HOCl + NH3 H2O + NH2Cl (monochloramine)

HOCl + NH2Cl H2O + NHCl2 (dichloramine)

HOCl + NHCl2 H2O + NCl3 (trichloramine)

When these reactions are complete and an equilibrium is found, all the avaliable chlorine will be either free or combined. The total residual chlorine (TRC) is the sum of FAC and CAC. While both exist in sanitation, FAC is preferred for its ability to be a more effective disinfectant. The only drawback is that FACs produce a bad chlorine smell and can produce trihalomethanes that are toxic to humans. Chloramines, although less effective, are more popular in public water treatment for this reason alone. Many water treatment plants have opted to replaced the use of toxic chlorine gas with sodium hypochlorite, the same compound found in household chlorine bleach like Clorox. If you've ever let a solution of chlorine bleach dry out, a flaky white reside is usually seen. This is a mix of common salt (NaCl) and an alkali washing soda, sodium carbonate (Na2CO3). Over time sodium can build up in the tank water; thus, requiring an 100% system water purge every so often. It is important to know how your water is prepared so that you can know exactly how to treat the water for your goldfish.  

Understanding why dechlorination is necessary

As you just learned, chlorine is a disinfectant that keeps our water safe for consumption by killing living cells that could harm us. By bonding to the cellular walls of microorganisms, chlorine can halt cellular membrane-associated functions, diminish the wall's integrity releasing all internal organelles, or pass through the membrane and disrupt basic cellular functions. All of these events result in the death of the microorganism. Unfortunately, chlorine and chloramine do not know the difference between harmful bacteria and goldfish. When goldfish are bathed in chlorine-treated water, they experience the same thing as other microorganisms (except on a larger scale).

Chlorine and chloramines are very toxic to fish and other aquatic species at low concentrations. Amounts higher that 0.05 ppm can cause acute necrosis of the gills and exterior body parts. As chlorine passes through the gills of the goldfish, multiple cells that work to acquire oxygen for water are being destroyed. Chloramines, on the other hand, have the ability to pass directly in the blood stream where it attaches to the oxygen-transporter protein, hemoglobin, located in red blood cells. The protein is still able to acquire oxygen but is unable to release it to the right places. This is because chloramine increases the protein's affinity for oxygen. As the protein continuously holds on the the oxygen, organs failure increases due to oxygen deprivation. Essentially, suffocation tends to be the end result. Chlorine removes the ability for oxygen to be acquired by killing the cells needed for the process.  Even when oxygen is available in the blood stream, chloramines prevent the oxygen from getting to vital organs.  

How to remove Chlorine and Chloramines from the source

Now for the more challenging question. How are we to remove chlorine and chloramines? There are three major methods of doing so in aquatica, including: chemical treatment, heavy aeration, and using activated carbon filters. Each of these methods has its own pro and cons. With an explanation, you can determine the best route for your aquarium. 

Chemical Treatment 

By far, the most popular method of dechlorination is the use of the reducing agent known as sodium thiosulphate (Na2S2O3). When added to chlorinated waters, sodium thiosulphate reacts with hypochlorous acid in multiple ways depending on pH. Here are a few of those reactions:

Na2S2O3 + 4 HOCl + H2O 2 NaHSO4 + 4 HCl

Na2S2O3 + 4 HOCl + H2O Na2SO4 + S + HCl

Na2S2O3 + 4 HOCl + H2O Na2S4O6 + NaCl + NaOH

Sodium thiosulphate then reacts with the previously produced hydrochloric acid (HCl) to yield sulphur dioxide (SO2), salt, and water. Warning the sulphur dioxide produces a foul, rotten-egg smelling odor. Don’t be alarmed, your goldfish will not be harmed just stinky for a little while.

Na2S2O3 + 2 HCl 2 NaCl + H2O + S + SO2

Keep in mind that sodium thiosulphate will also react with chloramines, releasing ammonia (NH3) or ammonium ion (NH4+) depending on the pH of the water. At a ph greater than 7, there will be a release of toxic ammonia. At a low pH, the ammonia that is produced will reduce to form the less toxic ammonium ion. This release of ammonia/ammonium ion must be dealt with separately as sodium thiosulfate doesn't convert the toxins to a less dangerous compound.

Na2S2O3 + 4 NH2Cl + 5 H2 2 NaHSO4 + 4 NH3 + 4 HCl

Na2S2O3 + 4 NH2Cl + 5 H2 Na2SO4 + NH3 + HCl + S

Since oxygen is required in these reactions, chlorine and chloramine removal will deoxygenated your waters. These dechlorination reactions do take time, in certain circumstances, to remove chlorine from the water. Although it is not toxic, sodium thiosulfate does require more time than other dechlorination chemicals to process, so please do not add the reducing agent directly to the tank water as it might not have removed all the chlorine in time. For these reasons alone, water should be pre-mixed and aerated before adding it to your aquarium.

Heavy Aeration

This method of dechlorination involves the use of an air pump and stone to create vigorous bubbles that break the water's surface so chlorine can escape into the air. It is usually suggest to aerate the water for at least 24 hours. However, if your chlorine concentration is high this process can take a longer. Chloramines, on the other hand, will not disapate even with heavy aeration. Since many municipal water treatment centers have switched over to the more stable disinfectant, chloramine, many people are unable to used this dechlorination process alone.                  

Activated Carbon

Activated carbon filters are very effective at removing chlorine and chloramine. Carbon can also rendered ineffective if it becomes supersaturated with toxins. If this is to happen, these toxins leach off the carbon and dissolve into the water column. Effective water treatment requires large quantities of carbon and frequent filter changes which can becoming very costly. 

Although determining your water source's parameters can be a little tricky, figuring out the right method to treating your freshwater will give your goldfish a good head start to living in the environment you've provided. 

Happy Goldfish Keeping!
- Nikita


American Chemistry Council. Chlorine Chemistry. Retrieved June 15 2015.

American Water Works Association. Water Chlorination/Chloramination Practices and Principles. Retrieved June 16, 2015.

Calomiris, Jon J., Cristman, Keith A. Scientific America. How does chlorine added to drinking water kill bacteria and other harmful organisms? Why doesn't it harm us? Retrieved June 15, 2015.

Emma. Koko's Goldfish. Keeping Goldfish: A BREIF GUIDE FOR NEW OWNERS. Retrieved June 10, 2015.

Lynx, Jennifer. Solid Goldfish. Goldfish 101. Retrieved June 11, 2015.

Lynx, Jennifer. Solid Goldfish. Goldfish Care Basics: Tank Size. Retrieved June 11, 2015.

Lynx, Jennifer. Solid Goldfish. HOW TO SET UP A GOLDFISH TANK. Retrieved June 11, 2015.

Sharon (shakaho). Koko's Goldfish Forum. Kokos Goldfish Forum Guidelines for Healthy Goldfish. Retrieved June 10, 2015.

Rand, Brenda. Goldfish Emergency. 10 Steps to Goldfish and Koi Keeping - Step 4: Freshwater Source. Retrieved June 14, 2015. 

Rand, Brenda. Goldfish Emergency. 10 Steps to Goldfish and Koi Keeping - Step 5: Water Treatment. Retrieved June 14, 2015. 

The Goldfish Tank. Goldfish Care: How to take care of goldfish. Retrieved June 10, 2015

Tikkanen, Maria W., Schroeter, John H., Leong, Lawrence Y.C., Ganesh, Rajagopalan. Guidance Manual for the Disposal of Chlorinated Water. Retrieved June 16, 2015

Larson, Gary L., et al. United State Environmental Protection Agency. Toxicity of Residual Chlorine Compounds to Aquatic Organisms. Retrieved June 16, 2015

Von G, Lynda;  Wellman, Shannon. Koko's Goldfish Ten Step to Healthy Goldfish. Retrieved June 10, 2015. 

Wetman. The Skeptical Aquarist. Dealing with Chlorine and Chloramine. Retrieved June 15, 2015

Zillich, John A. Journal: Water Pollution Control Federation, Vol. 44, No. 2. Toxicity of Combined Chlorine Residuals to Freshwater Fish. Retrieved June 16, 2015.

Water Parameters & Test Kits

Step 3: MAINTENANCE of Water Quality

Published July 21, 2015

As enthusiasts, it’s essential to keep our tank's water free of toxins to prevent unhealthy goldfish. Although you could have a strong colony of beneficial bacteria and water changes preformed regularly, we have learned that tap water might not have the ability to support life. Goldfish need a proper amount of minerals, adequate oxygen levels, and toxin-free water to sustain a healthy life. The water parameters (ammonia, nitrite, and nitrate) should be tested periodically on established aquariums to ensure that each level is perfectly balanced. Also, make sure to test the tank water against the tap water to make the correct changes in general hardness and carbonate hardness when doing water changes. 

Listed below are main water parameters that enthusiasts should be checking regularly. In each, there is a description of what range goldfish are compatible with and "out-of-range" symptoms. 


Goldfish prefer a consistant temperature between 64 ͒ F and 74 ͒ F. Consistancy, in this case, meaning that same temperarure everday durning the same time of day; if temperature is to change it should be gradual as to not shock the fish. Since goldfish are cold-blooded, at lower temperature they go into a dormant state. In dormancy their blood flow rate slows, they breath less oxygen, eat little to no food, and hover near the bottom of the tank or pond. This amazing atribute keeps goldfish safe from toxins, bacteria and parasites, and pH swings. Beneficial bacteria also thrive in the same environment as the goldfish and act in a simular manner when exposed to lower temperatures. Both begin dormancy at 64 ͒ F and reaching full dormancy at 45 ͒ F, no longer needing food to survive. Lowering or raising the temperature will not cause a spike in the cycle if food avaliability is lowered at 64 ͒ F and stopped at 45 ͒ F. A higher temperature will adversly affect your goldfish. Ammonia, nitrite, and nitrate are more dangerous at higher water temperatures with a higher pH and heavily oxygenated water. Since the temperature increases blood flow, toxins are able to move faster through the blood stream affecting the goldfish in a shorter amount of time.

Ammonia (NH3) / Ammonium Ion (NH4+)

Ammonia, or ammonium ion, is produced from fish waste, body secretions, and uneaten food. It is important to understand that ammonia and ammonium ion exist in an equilibrium determined by pH. At a pH above 7, the more toxic ammonia (NH3) concentration will increase and have a detrimental effect on the goldfish. A a low pH, the equlibrium will shift to the less toxic ammonium ion (NH4+). Even though one of more toxic and the other is less toxic, both compounds are still toxic at low concentrations; therefore, goldfish have a ammonia/ammonium ion tolerence of 0 ppm. High levels of ammonia affect the gills first by preventing proper breathing and causing gasping at the surface. Extended exposure affects the fins and body causing clamped fins and burns.

Nitrite (NO2-)

Nitrite is the second toxin produced in the nitrogen cycle. It is converted from ammonia by ammonia-oxidizing bacteria (AOB). Goldfish have a 0 ppm tolerance to nitrite. Nitrite is extemely toxic because it prevents the blood from carrying oxygen. Symptoms include brown or tan gills, rapid gill movement, and gasping at the water’s surface.


Nitrate is the third and final toxin in the nitrogen cycle. It is converted from nitrite by nitrite-oxidizing bacteria (NOB). Nitrate is not as toxic as ammonia and nitrite, but goldfish can only tolerate 20 - 40 ppm of nitrate. If nitrate concentration are allowed to increase poisoning will occur and goldfish will usually be in a bent or curled position.

Potential of Hydrogen (pH)

Potential of hydrogen (pH) is a unit that measures the acidity and alkalinity of an aqueous solution and is related to the hydorgen ion (H+) concentration. Numerically the pH is equal to the negative logarithm of the hydrogen concentration expressed in molarity (mol/L). A pH of 7 is neutral; above are basic solutions and below are acidic solutions. Goldfish prefer a consistant pH of 7.0 - 8.2. If pH swings occur the symptoms are redding of gills and/or buldging eyes. In extreme cases, bleeding from the eyes indicats a pH crash.

Carbonate Hardness (KH)

Carbonate hardness is the concentration of carbonate and bicarbonate ions in a given solution, in this case tap water. The concentration depends on the fresh water source and how the water is treated at the wastewater treatment plant. KH helps stabilize pH by contributing to the water’s buffering capability. Tanks with low KH will experience pH swings and decreasing oxygen concentration. Goldfish prefer a KH in a range of 100 to 150 ppm.

General Hardness (GH)

General hardness is the concentration of non-carbonate minerals, such as magnesium, calcium and other trace ions. The harder your water the higher degree of general hardness. These minerals are very important because they assist in the water’s ability to support life by providing the minerals needed for cellular function. For instance, calcium is important because it assists in the osmoregulation of the fish. Goldfish need an GH range of 150 to 200 ppm. 


Oxygen is essential for respiration. Higher levels of oxygen reside in waters that have a higher pH and KH. Goldfish require an oxygen concentration of 7 to 10 ppm.


Carbon dioxide is the by-product of respiration and degredation of waste. When it becomes supersaturated in the water, oxygen prevented from diffusing into the water column at the surface. This has an indirect effect on the buffering capability because oxygen is needed to form corbonate and bicarbonate. It can be battled by aeration and breaking the water's surface; but, if the O2 concentration is low, pH and KH are soon to follow.

Water Test Kits

While they are very helpful, water test kits shouldn't depended upon 100% due to their unreliability. In my opinion, testing the water's parameters is "must-do" for unestablished tanks, when new arrivals come in, and if any fish are showing signs of illness.  At these times, water testing your first line of defense when it comes to water quality. During cycling, unestablished tanks can become off balance as they progress and testing is needed to know where you aquarium stands. New arrivals may cause spikes in your aquarium's cycle because the waste load increased. It is also likely that a fish showing signs of illness might be due to unstable water parameters. I believe that water testing extremely helpful during these times, however constant checking is unnecessary. 

Reasons why I don't agree with constant checking before every water change are: 

  1. Water test kits relay on color charts to determine the concentrations of the various parameters. This means the test is subjected to the color perception of the user. Although we'd all like to believe that our vision is just fine, confusion about color matching can lead to human error. 
  2. Having a comparable standard for the color would reduce the human error in color perception, but I haven't seen this provided in any hobbyist kits. Knowing ahead of time what certain water parameter's concentrations look like color-wise would help in determining the actual concentration of the sample. Comparing the sample's color to a chart not provided by yourself is, simply put, guesswork. If you really want to up the accuracy, make your own standard with known concentrations and compare them with your aquarium's samples. 
  3. Although there are two options for testing your water's parameters, drip strips vs. drops, only one is truly acceptable for use. While drip strips are more affordable they can be faulty for several reasons. Drips strips have a tendency to be stored improperly. Exposure to light, moisture, extreme temperatures, or contaminates can lead to misreadings on drip strips. 

What to look for in a good kit:

  • Storage
  • Droppers 
  • Easy Instructions
  • Clear Color Indicator Chart
  • The Basic Reagents (Ammonia, Nitrite, Nitrate, KH, GH, and pH)

What to remember when testing:

  • Read all instructions before doing the test
  • Pay attention to hazard pictograms
  • Use gloves
  • Hold the bottle correctly
  • Read the meniscus
  • Rinse tubes

Learning to maintain the water quality of a goldfish aquarium is an essential tool to the hobbyist. It is essential that enthusiast understand water parameters and how they affect the goldfish and the environment in which they live. Remember, since we are providing them with their home, our goldfish depend on us to keep them in a toxin-free aquarium. Observe your goldfish, learn what they like and dislike, and develop an ecosystem in which they can thrive. 

Happy Goldfish Keeping!
- Niktia


Emma. Koko's Goldfish. Keeping Goldfish: A BREIF GUIDE FOR NEW OWNERS. Retrieved June 10, 2015.

Sharon (shakaho). Koko's Goldfish Forum. Kokos Goldfish Forum Guidelines for Healthy Goldfish. Retrieved June 10, 2015.

Rand, Brenda. Goldfish Emergency. 10 Steps to Goldfish and Koi Keeping. Retrieved June 10, 2015. 

The Goldfish Tank. Goldfish Care: How to take care of goldfish. Retrieved June 10, 2015

Von G, Lynda;  Wellman, Shannon. Koko's Goldfish Ten Step to Healthy Goldfish. Retrieved June 10, 2015. 

Oxygenating the Water Column

Step 4: Breathin' Easy

Published August 3, 2015

It is a common misconception that goldfish do not breath oxygen.  Probably brought about by the misunderstanding that goldfish do well in fishbowls without filtration or aeration.  On the contrary, goldfish need oxygen to breath. It can be provided by plants during photosynthesis, water surface action, or an air stone and pump. 

When using an air pump and stone to aerate the water column, air is pumped though a porous stone that blows tiny bubbles up to the water's surface. Many think that as the bubbles rise oxygen diffuses into the water. While this is slightly true, this diffusion does not provide nearly enough oxygen. What’s really happening? The disturbance at the surface, caused by the tiny bubbles breaking at the water's surface, allows oxygen to dissolve into the water. This surface action allows supersaturated gases, like carbon dioxide, the ability to move to the surface of the water and escape. In the escape, oxygen can exchange places with carbon dioxide and diffuse into the water. 

Utilizing plants in the aquarium is another way to oxygenate the water column. During photosynthesis, plants use carbon dioxide, given off as waste from goldfish, to covert light energy into chemical energy to fuel various metabolic functions. However, when the light is off the plants release carbon dioxide. This downfall builds excess carbon dioxide in the water column. Since its density is higher than water's, carbon dioxide sinks near the bottom of the tank where it must be circulated back to the top to be released through surface action. An air stone and pump helps this dilemma. Alternatively, you could use a water pump (HOB or internal/external intake) to pull the water from the bottom of the tank to the top expelling CO2 and other gasses. As the water is released over the top, the surface action from the splashing water allow the unwanted gases to escape and oxygen to enter. 

Although air pumps and stones are not essential, be wary of symptoms involving oxygen deprivation. If you ever notice you goldfish having increased gill movement, decreased activity, or gasping at the surface make sure to ask yourself these essential questions and adjust to your goldfish’s needs.

Is your water temperature in the comfort range?

Goldfish prefer the temperature to be 72° F - 75°F (22°C - 24°C). Anything above 82°F (28°C) will make your goldfish suffer. Besides, cooler water contains more oxygen than warmer water. Raising the temperature of the water gives oxygen atoms more energy to become excited and move around more. Combine this with adequate surface action and you've got major escape of oxygen form the water column. A higher temperature also increases the rate at which metabolic function is preformed in goldfish and microorganisms, alike. This greater consumption of oxygen decreases the overall concentration in the water since it is being used faster than it is replaced. Why not knock out two birds with one stone? Keep the water cooler to sustain the oxygen levels and have comfortable goldfish. 

Is your water too still?

Not having enough surface action can be due to not having a filtration system that pumps 10x the total volume of the tank and/or the outflow is too deep into the tank. If your filter is not big enough for your goldfish tank, you could either replace it with a larger one or add another filter to make up for the remaining GPH. If you filtration is up to par, you can try adjusting the outflow to spray water over the surface to create more of a disturbance. You could also use spray bars attached to the outflow that will even out the disturbance over the entire surface.

Does your tank have a small surface area?

Earlier I explained that creating a disturbance as the water’s surface allows CO2 and other saturated gasses to escape in exchange for oxygen. There are more chances for oxygen to diffuse into the water column if you have a large area for surface action to take place. Having an tall aquarium can be a little tricky because the smaller surface area doesn't allow optimal oxygen/carbon dioxide exchange required for the greater amount of depth. If your tank does have a smaller surface area try creating a greater disturbance at the water’s surface than usual.

By providing the right amount of surface disturbance you shouldn’t have any trouble giving your goldfish a breath of fresh air. 

Happy Goldfish Keeping!
- Nikita 


Emma. Koko's Goldfish. Keeping Goldfish: A BREIF GUIDE FOR NEW OWNERS. Retrieved June 10, 2015.

Sharon (shakaho). Koko's Goldfish Forum. Kokos Goldfish Forum Guidelines for Healthy Goldfish. Retrieved June 10, 2015.

Rand, Brenda. Goldfish Emergency. 10 Steps to Goldfish and Koi Keeping. Retrieved June 10, 2015. 

The Goldfish Tank. Goldfish Care: How to take care of goldfish. Retrieved June 10, 2015

U.S. Geological Survey. Water Properties: Dissolved Oxygen. Retrieved July 30, 2015

Von G, Lynda;  Wellman, Shannon. Koko's Goldfish Ten Step to Healthy Goldfish. Retrieved June 10, 2015. 

Water Pumps & Filtration

Step 5: Renewing Water Quality With Circulation

Published August 6, 2015

The main point of filtration is to convert fish waste to a safer form, circulate water, and create a surface action for oxygenation. In trying to mimic a goldfish’s natural environment, we utilize  three different aspects of filtration: mechanical, biological, and chemical. 

Mechanical Filtration

Typically the first stage in filtration, mechanical filtration is usually made up of porous sponges and micropads to physically trap particles of uneaten food, fish waste, decaying plant materials, and other muck that builds up in the aquarium water. The sponges and pads help prevent the biological media from becoming clogged before the bacteria have the chance to colonize. In a filter the sponges and pads are placed so that the pores decrease in size as the water moves through. This aids in larger particles getting trapped before smaller particles, making the system more efficient and less prone to clogging. Although the primary function of mechanical media is not a biological process, it provides a readily available food source that will promote the proliferation of beneficial bacteria. 

Biological Filtration

In the second stage, the biological filtration is the workhorse of the filtration process. Usually contained in media that a significantly high surface area (for example, ceramic rings or bioballs), the ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) convert ammonia to nitrite and finally to nitrate in the nitrogen cycle. Having a well function filter will encourage beneficial bacteria to proliferate and maintain strong colonies; leading to a strong cycle. If your media is extremely porous, you can also have some denitrification (removal of nitrate) in the deoxygenated parts of the media.  

Chemical Filtration

Chemical filtration is the only optional media that can be added to your filtration system and is defined as any substance that will change the chemical composition of the aquarium water. The most common form of chemical filtration used is activated carbon because it is a very porous material with a lot of surface area. Activated carbon attracts pollutants, odors, color, and dissolved organics which adhere to the carbon’s surface. Therefore, surface area and material absorbed are proportionate. However, since the surface area can be exhausted it can be hard to determine when the life of the activated carbon has ceased. If using this media alone in an un-cycled tank, the lifespan of chemical filtration can be very unpredictable.

What Type of Filter and Pump Should I Use? 

When thinking about what type of filter and pump, the most important question to ask yourself is how you should house your beneficial bacteria and its media. Basically you'll need a pump to pull water from an intake in the tank, push it through the media, and return the cleaned water back to the aquarium. Although most filtration systems come with the housing and pump, it is possible to build your own filtration system by creating the housing and using an external or submersible pump. When finding the right filtration system for your goldfish, make sure that it has a flow rate of 10X the volume of your aquarium. 

There are many types of filtration systems that are available to the general fishkeeping public but few of them great from goldfish. Here I'll go into more detail about most common filtration systems and how they relate to goldfish keeping. 

Filters Powered by an Air Stone

Sponge Filter

A sponge filter consist of a tube with the bottom half encased in a sponge. The portion of tube within the sponge has perforations that allow water to pass. An air stone and tubing is dropped into the center of the sponge filter tube so that it reaches the bottom. Powered by an air pump, the air stone breaks the air into tiny bubbles. As the bubble rise to the water's surface water is pulled through the sponge and out of the tube. The sponge houses the beneficial bacterial colonies that convert waste byproducts, ammonia and nitrite, to a safer form, nitrate. It is not recommended as a main filtration because it is not powerful enough to turn the water 10 times per hour. However, sponge filters are a great idea for temporary holding, young fry with low waste production, and additional biological filtration.

Undergravel Filter

Undergravel filters work in a similar manner as sponge filters except the tray where water passes through is below the gravel.  Water is pulled through the gravel where the beneficial bacteria are located allowing them to process the soiled water. These filters are generally not recommended because they can be difficult to clean and tend to trap excess waste in nooks and crannies of the gravel. These filters are not efficient enough, since they are powered by an air pump, to turn the water 10 times per hour.  

All-In-ONe Mechanical and Biological Filtration

Submersible Filter/Pump

Submersible filters/pumps can be good for additional housing for beneficial bacteria but have many drawbacks. Because the filter is being submerged it takes up valuable swimming space. In order to take up less space, these filters are usually engineered to be very small and do not have enough internal space to house a larger and more powerful pump. Since the recommended flow rate for goldfish is 10X the volume of the tank, it is not uncommon to require many of these filters to accommodate the bioload; thus taking up even more space. If this filter is going to be used, make sure that it has an external basket that you can put a sponge on to house some additional beneficial bacteria. Keep in mind that because the pump in inside the water, the motor might increase the temperature of the water (usually only by 2 or 3 degrees F). 

Hang-On-Back Filter (HOB)

Hang-on-back filters are exactly what it sounds like. These filters hang on the back of the tank wall with an intake inside of the aquarium where water will pulled up and through the filter media basket outside the tank. The returned water is cascaded over the tank's surface providing some aeration. It can be used as the only filtration as long and the water flow is 10X the tank’s volume. Since they tend to be small, you might need to have multiple filters on larger tanks.  Although it can house alot of beneficial bacteria the intake usually is unable to reach the bottom of the tank leaving "dead zones" where water is still. However, with the use of air stones and air pumps this can be overcome by providing more circulation. HOBs are relatively inexpensive and are very easy to clean. 

Canister Filter

Canister filters are an excellent choice for bio-filtration because they can contain a large amount of 'high surface area' media and have large enough motors to turn over the water 10 times. There are many levels within the canister filter that can be filled with any type of media, so the possibilities are endless. Many aquarist make use of ordering the chambers in specific positions to further filter the water mechanically with sponges and filter pads. This removes solid waste particles as to not clog the porous surface of the biological media. With this increased surface area on the sponges and media, a larger population of nitrifying bacteria can be maintained.  Canister filters can be cumbersome to clean because they are so large. With planted aquariums, if not cleaned often, these filters can become a 'nitrate bomb' due the increased amount of plant debris and excess detritus from snails the sponges are able to trap. If using this filtration system, you should have a flow rate that is 5x the amount of gallons in the tank since you are housing more beneficial bacteria.

Separate Housing for Biological and Mechanical Filtration

Sump (with or without Wet/Dry) 

Sump filtration consist of a large volume of water, underneath the aquarium, that contains chambers to hold biological media, tank equipment, and sponges and filter pads. This keeps the main tank free of excess equipment while offering biological filtration. Typically, water is captured by an overflow system that sends the water to the first stage of the sump where organic particles are filtered out by the mechanical media. The water then moves through a baffle, a series of right angles, that calm the water so micro bubbles can escape. Usually the second chamber contain an extensive amount of biological media. The water can be flush with the media or it can be trickled over the media as in a wet/dry sump. The trickling allows the water to the oxygenated before it reaches the aerobic bacteria but it also out-gasses the essential carbon dioxide that a planted aquarium needs. Before the last chamber there can be a refugium, a 'refuge' where organisms that can not survive in the main tank can thrive. In this chamber you can grow and protect live food from being eaten (for example, duckweed or Daphnia). You could also use this chamber as a grow out place for young plants that have yet to develop a good enough root system. In the third chamber there is a pump that will push water back into the tank; thus, the cycle repeats itself. Since goldfish’s bioload is incredibility large, this is a great option if you have an unlimited budget or love DIY projects. 

Fluidized Sand Bed Filter

Fluidized sand bed filters are by far an excellent choice for a filtration system. It works by moving the water through a sand bed. The sand has an extremely high surface area that can handle a heavy bioload. When the sand bed is fluidized, the nitrifying bacteria go to work.  As the water moves through the bottom of the sand bed the ammonia and nitrite are converted to nitrate by aerobic bacteria with the use of oxygen. If the tower is tall enough, the water is striped of oxygen allow the proliferation of anaerobic bacteria that denitrifies the nitrate to nitrogen gas. Being powered by either an submersible or external pump, this filter can drastically out-filter an HOB, canister filter, or sump. It can also be powered by a canister filter if it is placed down line.  As the bio-load increases, the sand bed filter can adjust to the weight by allow more water flow. If you have a planted tank the carbon dioxide is not stripped like it would be in a wet/dry sump filter. It is essentially self-cleaning since the sand scrubs the walls of the filter but it wouldn't hurt to mechanically filter the water with sponges before sending it to the sand bed filter.

Understand the different types of filtration and how they renew the water quality with circulation is essential to proper filtration in a goldfish aquarium.

Happy Goldfish Keeping!
- Nikita


Admin. Aquarium Supplies, Resources. Aquarium Fluidized Bed Filter Review; TMC V2, Merlin, Lifeguard. Retrieved August 3, 2015 

Austin, S. A. TropicalFishKeeping. Understanding Sumps. Retrieved August 4, 2015

Emma. Koko's Goldfish. Keeping Goldfish: A BREIF GUIDE FOR NEW OWNERS. Retrieved June 10, 2015.

FishScale. The Planted Tank. Sump vs. Wet/Dry vs. Canister. Retrieved August 4, 2015

gmacreef. Reef Aquarium Sump Tank Design. Retrieved August 4, 2015

Sharon (shakaho). Koko's Goldfish Forum. Kokos Goldfish Forum Guidelines for Healthy Goldfish. Retrieved June 10, 2015.

Rand, Brenda. Goldfish Emergency. 10 Steps to Goldfish and Koi Keeping. Retrieved June 10, 2015. 

The Goldfish Tank. Goldfish Care: How to take care of goldfish. Retrieved June 10, 2015

Von G, Lynda;  Wellman, Shannon. Koko's Goldfish Ten Step to Healthy Goldfish. Retrieved June 10, 2015. 

Water Changes & Maintenance 

Step 6: Keeping the System in Tip-top Shape

Published August 28, 2015

A routine water change is one of the most important things you can add to your maintenance schedule. Water changes allow soiled water to be removed and replaced with fresh treated water. Remember, anything wrong with your fish could be a representation of the water quality. Bad bacteria, de-oxygenated water, and toxins (among several other things) thrive in poor water conditions leading to the destruction of your goldfish’s health. Regular water changes are essential to preventing any future ailments your goldfish might have. It is a lot easier to do regular water changes than having to treat a sick fish from exposure to soiled water.

An ounce of prevention is worth a pound of cure.
— Benjamin Franklin


There can be some misconception that the filtration system will rid a fish keeper from having to do water changes. This is definitely false. The filtration system only houses the beneficial bacteria that quickly proliferate on the filter media and establish a strong nitrogen cycle. The stronger the colony, the less likely that bad bacteria will be able to form because they are out-competed for resources. Although the beneficial bacteria do a fantastic job of converting ammonia and nitrite to a less toxic form, high levels of nitrate are toxic if allowed to exceed 20 ppm. In a natural setting, the water’s current or aquatic plant life is able to remove the nitrates from the fish’s habitat. In aquatica, we don’t have these blessings; therefore, water changes are necessary to remove nitrates and keep their levels low.

The decay of excess fish waste and uneaten food indirectly contribute to the nitrate concentration as it is broken down further into various smaller molecules, like ammonia. If decaying plant leaves and uneaten food are left to rot ammonia is produced at a higher rate. If your beneficial bacteria are not well established they might not be able to keep up with the increased ammonia. Algae spores utilize ammonia as their 'fertilizer' to grow, resulting in a bloom. Cleaning out excess detritus and preforming regular water changes not only keeps the ammonia production down and nitrate levels in a safe range. 

After a water change, the minerals that make up the total water hardness start to deplenish as they is taken up by living organism. Plants, fish, and invertebrates preform basic metabolic function by using the calcium, magnesium, and other trace minerals that are available in the water column. This decrease by no means happens immediate but occurs over time. If the water is not changed often, or is only toped off occasionally, no minerals are being replenished. The water eventually looses its ability to sustain life. If using tap water or well water, these minerals will be replaced during the water change. If you use RO/DI water or the available water is too soft, you'll have to add these basic minerals to the water column. 

How Much Water Needs To Be Changed?

The old notion of doing a weekly 25% water change is dead, at least with a goldfish tank. The reason, nitrates eventually build up because not enough are being removed during each water change. I'll explain:

The Build-Up of Nitrate After Water Changes

(Initial Nitrate+Nitrate Added) - [(Percentage Water Change) X (Initial Nitrate+Nitrate Added)] = The Amount of Nitrate Left After A Water Change

Click to View Large

Let's assume that everyday your goldfish produce enough waste to amount to 1 units per day (unit can be in whatever unit you want, the numbers are more important for this example). At the end of the week the gross amount of nitrates is 7. Next you'll do a 25%, 50% or even 75% water change to lower nitrates. But, what happens to the concentration of nitrates may surprise you. You might think that you are getting rid of nitrates by doing these water changes, whether large or small. In reality, the only way to get rid of nitrates completely is to do a 100% water change during every routine maintenance. 

However, the point of do a water change is not to remove all nitrates but to keep them under control. As you can see with 25% water changes, the nitrates increase at a faster rate than 50%. But a 50% water change does not keep the increase nitrates as low as a 75% water change. Doing a routine 75% water change seems to be the key to keeping the nitrate levels stable over time. 

Ultimately, you'll never be able to keep the nitrates at a consistent level. Nitrates will continue increasing indefinitely unless something is consuming the nitrates. This can be handled in two different ways. If your able to make an anaerobic environment, denitrification can take place converting nitrate into nitrogen gas. A much easier way is to add terrestrial plants or floating plants to the system. Since these plants are exposed to air they are more efficient at utilizing nitrate than submerged plants. 


Although there are various methods to cleaning your fish tank, there are basics that should be done routinely to ensure the health of your aquarium. 

Scrub the walls of the tank with an algae pad.

This can be done with either a loose or magnetic algae pad. If using magnetic algae pad make sure to get one that floats. If you get one that does not float and if falls into the sand, you will have sand in the micropores of the pad. When you go to clean the glass, the sand will scratch the surface of the glass. Nevertheless, scrub in small circles and let the debris settle for about 15 mins. 

Sift though the substrate to allow the waste to settle on the surface.

If you  have a bare bottom tank, this step is unnecessary. Rake your fingers through the sand or gravel to stir it up any trapped debris. Allow it to settle before moving to the next step. 

Use a gravel vacuum to remove the waste

There are many types of gravel vacuums out there. The ones that I have seen most often are either hand pumped or hooked up to a sink faucet. I find that the hand pumped vacuum have more suction than hook-up vacuum. Which ever one you decide to choose, you will used both in the same way. With gravel, you will want to push the mouth of the vacuum into gravel. Don’t worry about the vacuum sucking up the gravel, once the vacuum has lifted the gravel it will fall. With sand, you want to have mouth of the vacuum about half an inch above the surface to not pull the sand through. Make sure to move around decorations and rock because waste tends to get trapped there if not cleaned often.

Clean out the filters and squeeze out sponges

Make sure to moderately squeeze your filter sponges in tank water and not in fresh tap water. The tap water contains chlorine and chloramines that will harm your precious bacteria. The main idea is that you want to maintain your colony while getting rid of excess mulm. If you have a canister filter or HOB, dump all the soiled water and replace with treated water.

Replace removed water with fresh dechlorinated water. 

Using a dechlorinator is extremely important because it converts harmful chlorine and chloramines to a safer form. If you have any trace amounts of ammonia, nitrite, or nitrate, dechlorinator will usually “lock” these for 24 hours as to not affect the fish but allow the bacteria to still process them.

Doing routine water changes and maintenance keeps your goldfish aquarium in pristine condition. Learning how to control nitrates with water changes, restore lost minerals, and removing excess detritus to prevent spikes are all necessary to providing your goldfish a great environment.

Happy Goldfish Keeping



Emma. Koko's Goldfish Forum. Keeping Goldfish: A BREIF GUIDE FOR NEW OWNERS. Retrieved June 10, 2015.

fi5hkiller. Koko's Goldfish Forum. Water Changes - How Often. Retrieved August 24, 2015.

Sharon (shakaho). Koko's Goldfish Forum. Kokos Goldfish Forum Guidelines for Healthy Goldfish. Retrieved June 10, 2015.

Rand, Brenda. Goldfish Emergency. 10 Steps to Goldfish and Koi Keeping. Retrieved June 10, 2015. 

The Goldfish Tank. Goldfish Care: How to take care of goldfish. Retrieved June 10, 2015

Von G, Lynda;  Wellman, Shannon. Koko's Goldfish Ten Step to Healthy Goldfish. Retrieved June 10, 2015. 

Substrates & Decorations

Step 7: Choosing Goldfish Friendly Ascetics  

Published September 5, 2015

Time for the fun part, decorating! Don’t get too carried away before you read this article. 

What Type of Substrate Should I Pick?

When picking the substrate, you want to make sure that you are mimicking the goldfish’s natural environment. Not only is it good for the well being of the goldfish by providing a stress-free environment, but you will also be able to see some natural behaviors that will make you adore them even more. 

Each substrate has its own benefits and drawbacks. Hopefully this explanation will help you determine which one is right for your goldfish aquarium. 

Sand can be a great substrate because it mimics the natural environment of the carp. It should be spread in a thin layer, no greater than one inch. Very fine grain sand can compact easily creating oxygen-depleted pockets making havens for anaerobic bacteria. These harmful bacteria produce toxic hydrogen sulfide gas which can be released by goldfish digging or routine cleaning. If you are considering sand, it is important to rake your fingers through when cleaning or employ some Malaysian Trumpet snails to do the sifting for you. 

Gravel, pea sized rocks, is the most common substrate that novice fishkeepers like to use. Although it is must in many tropical applications, gravel has a couple of drawbacks when used in a goldfish aquarium. Gravel has a lot of nooks and crannies that waste and uneaten food can be trapped easily in the spaces among rocks. There is also some concern that goldfish can get the small pieces of gravel stuck in their mouth when digging around in the substrate. 

River Rocks are very similar to gravel, when used as a substrate, in that it traps waste between the spaces. In this case, the spaces between the rocks are larger; therefore, trapping more muck than the gravel. If not cleaned often, this can cause spikes in your cycle. River rocks are more useful as a decoration than a substrate. Make sure the rocks are smooth and rounded so they don't catch and rip your goldfish's fins.

Crushed Coral is typically seen in marine or reef tanks. With the advantage of stabilizing the pH by increasing the KH, crushed coral could be seen as a great substrate if you have soft water. Unfortunately, the pieces can be extremely sharp causing issues for fish that like to dig in the substrate. OUCH! 

Bare Bottom tanks are a great idea if you want to have a sleek and modern style to your aquarium. The outside of the tank can also be painted if you wanted to add some color or simulate a bottom. It can be a healthy alternative to substrate because waste and uneaten food can be easily cleaned from the bottom or sucked up by the filtration. However, the natural instinct of the goldfish to dig through the substrate is taken away. So if you are interested in seeing natural behaviors, this might not be the substrate option for you. 

What Type of Decorations Should I Get?

Now that you've got the substrate down it's time to start accenting your goldfish's environment with natural or man-made materials. Just like when selecting a substrate, you need to look for what would provide stress relief. Here I've tried to asses the benefits and drawbacks of each type of decor. 

Live Plants are an excellent choice for creating a natural goldfish aquarium.  By providing dense foliage, you can reduce stress by giving them places to hide, relax, and explore. Although the positives are obvious, taking care of live plants can be challenging for the novice aquarist. It does take a lot of research and understanding, to be able to grow plants without growing algae. Goldfish also have a tendency to devour any live plants within the area. Essentially your nicely displayed plants can become a salad bar if you don't pick the right plants. It isn't impossible but does require more time on the aquarist's part.

Fake Plants are a great alternative to live plants if you don't have a 'green thumb'. When picking out fake plants it is best to use only silk plants without any internal wires that could poke your fish. Plastic plants can be a little too thick and sharp for clumsy goldfish who like to get lodged in between things. The good thing about fake plants is cleaning is relatively easy and it cannot become a salad bar. 

Driftwood can be especially pleasing either paired with live plants or alone. It can complement the plants by adding the final touch to nature aquariums. When alone the character of the wood really shines. Decaying plant material and detritus tends to get trapped in the crevasses of the wood. So, make sure to move around the driftwood when doing regular maintenance to remove the buildup.  Certain types of driftwood will leech tannins into the water. These tannins give the water a tea color and slowly lower the pH. Regular water changes help with removing tannins. 

Hollow Decorations are not a good idea for goldfish aquariums. If the hollow area is closed off to the outside water flow, the internal water is never replenished. As it becomes stagnant and oxygen depletes, harmful anaerobic bacteria can flourish. If the hollow area is open, large fish may attempt to swim though a hole that may be too small. Lesion and missing scales may be a result of trying to swim though a hollow decoration that is not appropriate for a goldfish aquarium. 

Put your mark on your goldfish tank. But, keep in mind what makes your goldfish happy. Provide them with a simulated natural environment and they will give you hours of entertainment in return.

Happy Goldfish Keeping!


Emma. Koko's Goldfish. Keeping Goldfish: A BREIF GUIDE FOR NEW OWNERS. Retrieved June 10, 2015.

Lynx, Jennifer. Solid Goldfish. Goldfish 101. Retrieved June 11, 2015.

Lynx, Jennifer. Solid Goldfish. HOW TO SET UP A GOLDFISH TANK. Retrieved June 11, 2015.

Sharon (shakaho). Koko's Goldfish Forum. Kokos Goldfish Forum Guidelines for Healthy Goldfish. Retrieved June 10, 2015.

Rand, Brenda. Goldfish Emergency. 10 Easy Steps to Goldfish and Koi Keeping. Retrieved June 10, 2015. 

Von G, Lynda;  Wellman, Shannon. Koko's Goldfish Ten Step to Healthy Goldfish. Retrieved June 10, 2015. 

Food Options & Feeding Schedules

Step 8: Providing Nutritious Meals

Published September 8, 2015

When considering food options for your goldfish it is extremely important to know what you are feeding, how much to feed, and methods of feeding. Just like you need a balanced diet, so does your goldfish. Misfeeding your goldfish can lead to all kinds of problems, including buoyancy issues, constipation, and weight gain. Here I'll tell you how to avoid these problems while feeding in a way that is easy for you and great for the goldfish. 

What Do I Need to Feed My Goldfish?

There are several choices for processed fish food available. Just keep in mind that goldfish eat just like humans and processed food can contain a lot of fillers that have little to no nutritional value. Choose food that have recognizable products and don’t contain ash (a byproduct of low grade seafood, scales and bone that is used as a filler).

When feeding my goldfish, I like to have a staple diet and add supplements as needed or as treats. I've found that most people generally use pellet food as the goldfish’s consistent stable diet. This is probably due to the wide availability of pellets with many different composition. When choosing pellet food make sure that is contains a variety of nutrients, the correct size, and is sinking instead of floating. 

Sinking pellets are of better use because they do not require the goldfish to come to the water’s surface to feed. When floating pellets are used, goldfish create a bad habit of sucking air at the water’s surface which can lead to swim bladder and buoyancy issues. If the sinking pellets have issues sinking or you only have floating pellets, you can soak the pellets in tank water for a couple of minutes and release them below the water’s surface. Skittish goldfish tend to feel more safe closer to the bottom and out of sight of predators. Coming up to the surface to feed on the floating pellets can be stressful because goldfish cannot see below them.

Many pellet food companies provide different sized pellets ranging from small to large. The goal is to provide your sized fish with the right sized pellet. Regardless of size, I like to only feed my fish small pellets. My logic is that larger size pellets can still get stuck in the goldfish’s digestive tract preventing the uptake of nutrients and causing constipation. With smaller pellets there is less restriction (especially if the pellets are soaked) and nutrients are more easily absorbed.  

Now on the flake food. It is not uncommon for people to get fish flakes with their first goldfish. This is yet another decision made in ignorance or at the advice of an uninformed local fish store employee. Flake food floats causing the goldfish to come to the water’s surface to feed. Exactly like feeding floating pellets, goldfish are subjected to buoyancy issues because they're gulping in air. There are also some rumors that because flakes are so thin and papery nutrients leach out in the water. Flakes, that have not been eaten, can be sucked into the filter causing buildup and leading to a decreased flow rate.  At this point the fish flakes are pointless because they are dissipating in the water or being sucked up by your filtration system before the fish have a chance to enjoy.

Gel Foods are by far the best staple food that provides balanced nutrition because it is easy on the digestive tract and can be absorbed readily. Before there were mass produced gel foods on the market, many hobbyist made their food at home with a variety of ingredients; however, it might not be a nutritionally balanced as commercial brands that we have today. The most popular gel food for goldfish is Repashy’s Soilent Green and Super Green. These different formulas can be blended for the desired effect. It can be modified for young and old goldfish. Certain recipes can prepare goldfish for spawning or can increase growth in fry. Gel foods are well rounded and extremely versatile because it can be the base to any addition or combination of foods, minerals, vitamins, supplements, or medicines that your fish needs.  

Supplemental foods are just that, it completes and rounds out goldfish's diet. They are meant to provide specific nutrients and vitamins in the diet that should not be given in excess. In the case of protein supplements, too much can increase the bioload, or waste production, causing spikes in the cycle. So, it is important to keep the quantities of supplemental foods under control. Although most supplemental foods provided great nutrition, some are generally useless because of how they are prepared. An example would be freeze-dried foods. These tend to hold a lot a air even if they are soaked. As we already know, goldfish and gulping air do not mix well. The freeze drying process also renders the product devoid of nutrients making this supplemental food not a good choice. Good supplemental foods include: 

Frozen foods: Includes bloodworms, daphnia, brine shrimp, and many others. Great because they provide high protein which can be great for growth in fry or show fish.

Veggies: Includes kale, spinach, cucumbers, broccoli, edamame, peas, and many others. Can be used to help with buoyancy issues and constipation. Keep in mind that vegetables are not a fix all for these issues.  

Fruit: Great as a very small snack but should not be given on a regular basis because of high sugar content. 

Never feed your goldfish anything that is canned or contains pickling liquid and/or salts. In the wild goldfish do not eat dairy or wheat-based products; so don’t feed these items either. 

How Much Should I Feed My Goldfish?

If you’ve already kept goldfish than you probably know how these little water piggies work. Goldfish always seem hungry because of their persistent scavenging behavior. In the wild, carp spend most of their time grazing and digging in the substrate looking for food. Because food is so scarce in the wild, goldfish eat inconsistently and are constantly searching. So please do not be fooled into overfeed by your goldfish.

It is recommended that you feed your goldfish 0.5% to 2.0% of total body weight. The reason that I didn’t say to feed in a time limit is because each goldfish can be shaped differently. Some are long and thin while others are robust and stout. Weighing each of your fish and feeding based on that weight will give you more accurate results if you are trying to raise fry, increase growth in a show fish, or have changing water temperatures. Weighing each month should account for increased weight; therefore, you should adjust feeding mostly. Typically, 1% (for pellets) and 2% (for gel) are what most people choose to feed if there is no prospect in mind. 

What Method Should I Take to Feed My Goldfish?

It is important to mimic how goldfish would eat if they were in the wild. This means avoiding feeding in one go at all cost. In their natural environment, the foods that are available are in small amounts; therefore, when goldfish come across an abundance of food they tend to over indulge and eat beyond capacity. Overfeeding can cause the goldfish to gorge resulting in an impacted intestinal tract. Connected to the intestinal tract is the swim bladder. When the intestinal tract is working efficiently, fish are able to stay afloat and swim with ease. However, when the intestinal tract is running slow, floating issues may ensue because there is no gas exchange between the intestinal tract and the swim bladder. 

Now say that you have been overfeeding and your goldfish have become constipated. Some people will recommend that not giving your goldfish for a day or two will relieve the constipation and allow things to flow smoothly. When your goldfish is constipated there is no gas exchange between the swim bladder and the intestinal tract. Furthermore, fasting you fish will result in no gas exchange either because there is no food to stimulate the beneficial bacteria inside that help digest food to produce gas. Fasting can also lead to a spike in the cycle because there is no waste being produced for a time being. As we know the nitrifying bacteria residing on the filter media depends on the decomposition of waste to ammonia and nitrite to survive. Starving your goldfish will starve you beneficial bacteria. Either way you look at it, its a lose-lose situation and definitely not recommended. 

To evade constipation and buoyancy issues, it is important to feed your fish consistently and less often; about three to six times a day. Now for people who are not home all the time this can be challenging. Never fear though there are automatic fish food feeders that you add to the top if your tank. Automatic feeders contain wells that release food at the set intervals of your choice. I’ve read that using an automatic feeder improves the activity of goldfish by keeping them anticipating the upcoming feast. 

Providing a nutritional balanced diet should give a healthy goldfish for years to come. 

Happy Goldfish Keeping!
- Nikita


Emma. Koko's Goldfish. Keeping Goldfish: A BREIF GUIDE FOR NEW OWNERS. Retrieved June 10, 2015.

Lynx, Jennifer. Solid Goldfish. Goldfish 101. Retrieved June 11, 2015.

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Sharon (shakaho). Koko's Goldfish Forum. Kokos Goldfish Forum Guidelines for Healthy Goldfish. Retrieved June 10, 2015.

Rand, Brenda. Goldfish Emergency. 10 Easy Steps to Goldfish and Koi Keeping. Retrieved June 10, 2015.

Von G, Lynda;  Wellman, Shannon. Koko's Goldfish Ten Step to Healthy Goldfish. Retrieved June 10, 2015.