Goldfish Care: The Complete Guide


Having those beautiful goldfish swims idly around in your aquarium can be a source of calmness amidst the chaos of general life. And if you are into astrology and Vastu, goldfish are one of the most auspicious pets to have in your home.

But, take our words for it, having goldfish as pets are not as straight forward as it may seem. There are some systemic details on how to set up water tanks, technical details on water parameters, food, and details on different diseases you may encounter in your pet keeping journey, that you must know in order to have a thriving beautiful world for your pets.

So, whether you are a new owner or a seasoned goldfish enthusiast, we have compiled a detailed, point by point research that will definitely help you start, maintain and even grow your aquarium into the complete miniature water ecosystem of your dreams.

Tank installation: How to build a proper home for your goldfish

Size of the tank

Look away now guys. Size does matter. And yes, the bigger it is the better. There, someone had to say it.

If you can afford a huge artificial pond in your backyard, that’s the best. For the rest of the peasants, grinding out a 9 to 5 job, the aquarium is the best home for our goldfish.

Here are the parameters that dictate the size of the tank you need:

  • The size and the age of the goldfish when you buy them

Make sure that when you get your goldfish from the pet shop, they are young and small so that they have a lifetime to grow forward too. This way you can start with a smaller aquarium too.  The obvious downside however is, you will need to upgrade to a larger tank as the goldfish proceed to grow.

  • The potential size to which the gold fish may grow

There is a myth in regards to the size of the goldfish: Goldfish grow to the size of the environment. It is true that if you put a goldfish in a fishbowl and simultaneously put another goldfish in a pond, the pond goldfish will far outgrow the fish in the bowl. But, it is not because the goldfish grows into its environment. It is because the environment or the lack of an optimal environment stunts the growth of the goldfish. Thus it is important that you take into consideration the potential size of the goldfish may grow to.

For example, A Black Moore goldfish can grow up to 6 inches naturally. Hence, a 30 gallon/114 liters tank is optimum for two of them. However, a common goldfish can grow well 8ver a foot long. So you need to take that into consideration too. There may not be any hard and fast rule as to the exact numerical parameters of the tank you have to use, but many seasoned goldfish enthusiasts believe that 4 times the length of the potential size of the goldfish is the way to go.

  • Type of goldfish and the number of goldfish

It goes without saying, the more the goldfish you have, the bigger the aquarium you need. And goldfish grow quite big over the years. Hence, don’t go forward and buy 7 goldfish on your first outing. Be miser.

Also, keep in mind that the more slender common goldfish grow larger than the rounder fancy types. Hence, you will be needing a bigger tank for the common type.

  • Conclusion

After reading all the truckloads of information presented above, you might still be unclear: “How big an aquarium do I need then?

Well, if you have been scavenging the internet you may get data like 20 gallons per fancy fish, 30 gallons per common, and 12 gallons extra per every goldfish you add. But that is simply not true.

If you are searching for a definitive, one sentence answer, trust me, you will not get a correct answer.

But, if you still put a gun to my head and ask me the same question, I would suggest, start with a 75 gallon to 125-gallon aquarium if you want your goldfish to be growing and healthy. Keep the number to the minimum. Don’t pack the aquarium with goldfish of all varieties. Until you become more experienced keep the size to the maximum and number and variety to the minimum.

Keep it simple silly.

Material of the Tank

Basically, you have two options when it comes to the material put if which the tank is made: Glass and Acrylic.

Glass is budget-friendly and easily accessible. It can be cleaned easily and has an easy repair. But at the same time, it is easily fragile and has limited design options.

Acrylic tanks however can have various tank designs. If you are also looking to add some character to your living room, acrylic is the way to go as they also offer the option to be rimless. They are less fragile and lighter. But you do require special kind of foam or sponge to clean the acrylic tanks. They are also easily scratchable and their repair could cost you more bucks than the ordinary glass tanks. 

Aquarium substrate

Aquarium or tank substrate refers to the foundation of your tank i.e. what you choose to place at the very bottom of your tank. There are various types of substrates in the market to choose from. But you should keep in mind the pros and cons of each when you choose to lay down the bade of your aquarium with a certain substrate.


Gravel probably is the most used substrate in a goldfish tank. They do not just look sleek and clean but they also have a wide variety of colors, sizes, and also materials.


  • Gravel units have spaces between them. That allows a vital place for the beneficial bacteria to grow in the tank.
  • Space also allows for the anchorage of aquarium plants.
  • Goldfish are naturally bottom feeders and also like to move and fiddle a lot. So, they have a high chance of getting unwanted particles stuck in their mouths. Having proper pea-sized gravel makes it easier as compared to other substrates to not get stuck in the mouth of the goldfish.
  • Gravel is much easier to clean or vacuum than sand.
  • Gravel looks sleeker and cleaner aesthetically and multiple layers of gravel also act as biological filters.


  • Improper sized gravel can easily be gulped down by goldfish leading to choking 
  • Cleaning the gravel substrate is an arduous process that should be done more frequently as it is a good trap for all kinds of gunk inside the tank. And you will need to empty the tank for cleaning the gravel properly 
  • Gravel can act as a reflector of sunlight inside the tank leading to temperature increases.


If you choose sand as the substrate be careful of the following things.


  1. It is not your typical sand that you may get a handful from anywhere. The aquarium substrate sand is high quality soft sand.
  2. Sand is compact as compared to gravel. So it is better suited for the anchorage of plants. It prevents food getting stuck at the bottom and makes fir easier feeding for the goldfish.
  3. It doesn’t allow waste products to get collected at the bottom making for easier cleaning.


  1. Sand can be more easily disturbed by the fish and hence it has more chance of getting the entire tank dirtier.
  2. It can be a bit difficult to clean. With time, sand facilitates the growth of pickets that act like spaces filled with toxins and wastes that can be easily let out into the water.

Bare bottom

Well, if you have the personality of a white bread, you could just let your tank be bare bottom. Just joking. The bare bottom tank can and does have it’s own pros and cons.


  1. Goldfish are restless fish that like to move around and fiddle. Having a bare bottom allows them more space.
  2. Easier to be kept clean.
  3. Lesser chances if the fish swallowing up sand or gravel.


  1. Bare bottom tanks are more likely to develop harmful algae due to the lack of substrate.
  2. It gives your tank an artificial feel. This may alter the behavior of the goldfish.
  3. Higher chances of cracking the bottom.

Lights and darkness

Lights in the aquarium are not just your fancy decorations. Here is a thing you may not want to have read in a fish blog: fish are meant to be in the wild. Since we have decided we want to have goldfish as our pets, it is our duty to keep our tanks as closely imitable to the natural ecosystem that our pets should have grown in. And there are very fewer things more important than light in any ecosystem.

So yes, your aquarium does need lights and it’s much more than your fancy aesthetic decoration.

Goldfish are diurnal animals and they have no eyelids. They remain active in the day and rest/sleep during the night. Their feeding patterns are also governed by light. The aquarium lights help to mimic that inside your tank and helps maintain a natural circadian as well as feeding cycle.

Why do I need lights in my aquarium?

  • Artificial light helps mimicking the natural pattern of light the fish are used to. So it helps in maintaining a proper sleep wake up pattern.
  • It helps in maintaining a proper eating pattern.
  • In the lack of lightening, goldfish do not acquire their natural coloring and may have a faded look.
  • Proper lightening helps in the check of unwanted algae inside the tank.  
  • Light is important for the plants in the aquarium that in turn help to maintain a proper bio ecosystem inside the tank giving it a natural feel

How much light is required inside the tank?

If you have a tank that has plastic plants and the size of the tank is also small, 1 to 2 watts per gallon of water is sufficient.

However, having real, live plants does make a difference. The planted aquariums may need up to 2 to 5 watts of light per gallon of water.

What kind of light do I put in?

As we have been saying since the beginning, the environment inside the tank should mimic the real ecosystem. So, you need to have a light that imitates the sunlight.

Wait what does that mean?

It means you will be needing a full spectrum light. A full spectrum light is a light that has all the wavelengths as contained by the sunlight, that is, from blue to red.

Do not use incandescent bulbs

These bulbs were widely used in homes as well as aquariums before modern lightning came in. These bulbs have a yellowish tinge to them and emit very high heat too which causes disturbances in water temperature. So, avoid these bulbs altogether.

LED lights

Recently their use in tanks has been growing. They are cheaper to run and more energy-efficient and are softer to the eye too. They may however cost you more while upfront buying.

Fluorescent lights

Traditionally the most used and also the most versatile lighting options in the tank. They come in various sizes, powers, and options.

Actinic lights

These are specific wavelength lights. These are specially used for helping in photosynthesis of marine plants and penetrate deep depths. But, these come with a slight bluish tinge so you will need to add lights towards the reddish glow to balance out the spectrum. 

How long should I light the tank?

Here is the catch. Darkness is just as important to the ecosystem as much as the light is. So maintaining a healthy proportion of light and darkness is important. It all depends upon what kind of flora you have maintained in the tank.

If you have a tank with no plants, all you have to do is see that your fish get the replication of day and night. Lighting the tank for 12 to 16 hours then switching off the lights for 8 to 12 hours.

If you have a planted tank, however, lightening becomes far more important for photosynthesis too. Use strictly full spectrum bulbs or multiple bulbs to imitate different wavelengths. Diane Walstad in her book “Ecology of the planted aquarium” suggests 5 hours on, 4 hours off, and 5 hours on again for a planted aquarium.

Plants for the aquarium

A little green never hurt anyone.

Goldfish in their natural habitat live in heavily vegetated areas. And plants are just more than aesthetics for the aquarium. A fish living in an ecosystem close to its natural ecosystem is a happier fish. And you can see that happiness in a fish because it grows naturally to more natural size. Hence plants have psychological benefits.

Aquatic plants also provide shade.

 They provide shade for the fish to get some privacy from it’s tank mates and also the shade from the plants helps in reducing the temperature of the water.

However you must be careful while selecting plants for your aquarium. Goldfish are foraging fish and are hungry fish too. So, if the plants are not modelled properly, the fish can just devour them or pluck them apart.

Here are some plants that go very well in their aquarium.

  • Java fern

The Java Fern is a very versatile plant. It can grow in variety of lightening conditions, pH, and water temperature. And why it suits the tank so much is because it has hard leaves that the goldfish do not like to mow down upon.

  • Java Moss

The Java moss grows rapidly in a higher intensity light. And it grows moderately in a lower intensity light. Also, it requires to be anchored to some solid substrate like gravel or drift wood which leads to it’s chances of being dislodged by the goldfish to a minimum. However the goldfish may nibble on it a bit but this grows fast enough to grow again to a full.

  • Amazon sword:

The goldfish love the taste of the leaves of the plant. However, the plant grows rapidly enough to maintain with the nibbling habit if the goldfish. Their growing range also fits perfectly with the parameters that the goldfish requires.

  • Duckweed:

Duckweed grows terribly fast. So fast that if you don’t look after it, it may take over the tank under your nose. And that is not the only problem. This is a floating plant, so if you don’t watch it properly it may end up blocking the surface of the tank and hence impeding the natural sunlight. And here also lies it’s strengths. The goldfish love chowing down on the duckweed leaves that helps to offset the rampant growth of the plant. And it also requires no anchorage as it is a floating plant.

  • Water Sprite:

Water Sprite grows too fast. And the goldfish love to eat it. But if the water sprite finds it’s right environment, it will grow too fast despite the goldfish nibbling down at it. This plant however is versatile because you can use it both as a floating plant or an anchored water plant 

  • Hornwort:

This bryophyte has needle like rough leaves which deters the goldfish chewing them down. But, you may have to trim down the hornwort to keep it in length with the tank. These do best in gravel substrate.

  • Vallisneria Spiralis:

You will need a week or two after planting this for the roots to be strong enough to withstand the assault the goldfish generally unleash on plants. And you will need fine gravel for it. Vallisneria looks like grass with thicker and denser leaves and can grow upto 30 inches in height or even more 

  • Wisteria:

Just like every other plant in this list Wisteria grows fast enough fir the goldfish to nibble down at it regularly. These need fine gravel substrate and their roots grow thick and dense fats.

  • Water Lettuce:

This is a floating plant and if not kept under control these can grow large and block out the light entering through the surface. But water lettuce are easy to look after and don’t require any substrate to grow or hold on to.

If you want to add some character to the tank, you may want to add some driftwood in it. But make sure that drift wood provides extra base for the algae to grow and can also change the chemical component of the water Hence, it may be advised to not overdo when it comes to driftwood.

Water parameters

The most important factor for an organism to thrive is the ecosystem it lives in. Goldfish are no exceptions. Hence testing water parameters regularly to track the water condition and keep the unnecessary pollution in check becomes vital. If you have a newly set up tank, before the nitrogen cycle has naturally set in, water tests must be done frequently. Otherwise, once a week atleast is necessary to detect and avert potential damages to the goldfish in the future.

Here are the parameters you need to check up regularly:


Like almost every aquatic animal, goldfish are ammonotelic in nature i.e. they excrete ammonia as their main waste product. But ammonia is highly harmful for living organisms, especially goldfish are very sensitive to even the low levels of ammonia.

Over time, the tank has a “Nitrogen cycle” set up in it. A group of friendly bacteria inside the tank setup a cycle that converts the harmful ammonia into more liveable forms. But, a new tank requires time for the nitrogen cycle to set in.

Thus water testing and frequent water changes becomes a necessity.

Ammonia levels should be at 0 ppm or 0 parts per million in an established tank and upto 0.06ppm in a new tank. Anything over that should beckon water changing.

Ammonia can be tested by using API Ammonia test kit which is a liquid reagent or master test kit.


Now Nitrite is the immediate step after ammonia in nitrogen fixation cycle.  That means, the bacteria in an established water ecosystem convert the ammonia to nitrites first.

The nitrite particles are less harmful than Ammonia but still harmful enough for your goldfish.

An established tank must maintain a 0ppm concentration of nitrites while a newer tank can have as high as 0.75ppm of nitrites.


The nitrate is the most stable converted form of ammonia. This is the last step in the nitrogen cycle.

The nitrates don’t harm the goldfish unless like a dumbass you forget to change the water for too long.

Higher concertation of nitrates attracts algal bloom in the tank.

A range of 5 to 20 ppm of nitrates is okay in a tank but when the numbers start to push towards 40 ppm, a partial water change should be done immediately.


PH is the measure of how acidic or alkaline the water is.

Goldfish prefer a more neutral water PH i.e. a pH of 7 or close to 7.

A pH of 7.2 to 7.6 is tolerable.

Below at 6.5 pH the bacteria that contribute to the nitrogen cycle, start having trouble fixing the nitrogen into nitrate. And below a pH of 6, the nitrogen altogether stops.

Ammonia at higher pH more dangerous to the goldfish than Ammonia at lower pH.

Also, a sharp fluctuation in pH results in death. No kidding.

So, partial water changes must be done in order to not disturb the established nitrogen cycle and not fluctuate the pH too drastically.

General Water Hardness

Water hardness refers to the amount of magnesium and calcium salts present in the water.

Hard water has calcium and magnesium salts in it that require chemical reagents to remove the salts.

Soft water does also has calcium and magnesium salts in it but they can be removed by simple boiling.

Goldfish however do well in both soft as well as hard water but 200 to 400ppm of such salts falls in the ideal zone.

Chlorine and chloramine

The source of chlorine in your aquarium, mostly, is your tap water.

Chlorine overdoses can lead to the death of your goldfish.

Hence, what you will be needing is a dechlorinator.

A plain dechlorinator only reacts upon chlorines and the stubborn chloramine. So make sure, you get one that acts on both.

Carbonate Hardness

The carbonate hardness acts as the natural buffer for the pH in the tank. That means, when the carbonate level is maintained at an optimal level, the shifts in pH remains null. A high carbonate level doesn’t allow the pH of the tank to fluctuate. But the carbonate level beyond 200ppm may again increase the pH that makes it dangerous for the goldfish.

Water temperature

Optimal water temperature lies around 21 degree centigrade.

A range of about 15 degrees to 31 degrees can be tolerated by the goldfish.

However, rapid fluctuation in water temperature leads to death as the goldfish are cold-blooded animals, and their body temperature changes according to the environment. 

A water heater is thus more essential to the aquarium than it may look.

Aquarium filters

A good tank filter reduces the amount of work on your shoulders. As we have previously said, goldfish excrete ammonia as their major excretory products but cannot tolerate even low levels of ammonia in water. And since the water in the tank is static, the ammonia level can build up quiet quickly. Hence, good aquarium filter helps you keep that in check.

The water in the tank should be cycled/turned atleast 4 times in an hour. When you buy a new tank filter, you can see the litres/gallons of water cycled per hour labelled on the filter. But remain sure, these figures are going to drop. Hence choose a filter large enough that even the dropped or depreciated cycling power due to clogging meets your needs.

The principle behind the water filtration and cycling is that goldfish are bottom feeders that make a mess like there is no tomorrow. Hence, the mess at the bottom must be lifted upwards. There are basically two ways of doing so; either by using bubbles or by using the electrical power to pump up the water.

You can have a large variety of filters to choose from. You can have filters that physically lie outside the tank like: external canister filter, hanging filters. These require spaces around the tank and have hoses and inlets going into the tank.

Or you can have filters that lie inside the tank like: under gravel filter.


Goldfish are omnivores. You have the liberty of feeding them either plant or animal based food.

Let’s look into the factors you need to keep in mind to feed your goldfish properly and in right amount.

The purpose of feeding

The feeding amount and frequency depends upon what stage of goldfish pet keeping journey are you on. You may have small goldfish and maybe trying to grow them. Maybe you are trying to breed them or just trying to sustain them. The first thing is to pin point the purpose of feeding.


The dietary choices of the goldfish may very well depend upon the type of the goldfish. The fancy goldfish particularly are sensitive to the lack of live food in their diet as compared to the common fish.


  • Spring:

Spring is the breeding season for goldfish. Hence this is the time when their food must have higher protein content for eggs and milt production.

  • Summer:

Summer onsets once the breeding season is over. The higher temperatures mean the fish become less active and dry foods can sustain them for larger extents than other seasons.

  • Fall:

Now fall precedes winter. Hence, this is the time when the goldfish tend to stock up reserves. Hence high protein content with live and frozen food must be supplied at this time.

  • Winter:

Now you should not let the temperature drop beyond the comfort zone of the goldfish. But

Depending upon the temperature drop the fish may become inactive. Some fish may even refuse to eat altogether. So watch out for the fish response and feed them only when they start searching for it and become active. Otherwise, simple dry food in winter does the job.

 What do I feed my goldfish?

 There can be multiple options when it comes to feeding your fish.

Dry food

Dry manufactured and bottled or packetted food are the most readily available food for your goldfish.

They come in pellets, flakes and can be floating or sinking.

There are brands like Hartz Wardley, Hikari and Laguna that are easily available in almost every online sites.

These dry food are very high on protein content and will require the balancing out mineral contents from other vegetables. 

Storage can be a problem as they come in large bulks.

Frozen food

The good thing about frozen food is, it doesn’t require space to grow and can also be used out of season.

You can even get little goldfish prey like mosquito larvae, shrimps in frozen cubicles. However, due to drying and freezing they may lack moisture or proper water content and may contribute to abdominal discomfort or even constipation.

Gel food

These are the mixture of ingredients that come in powdered form.

Most goldfish enthusiasts consider this to be the ideal food for goldfish.

As they contain moisture and mimic the food the goldfish would have in their natural habitat.

These sink to the bottom and hence are apt for bottom feeders like goldfish.

These also have proper protein content and also vegetable matters.

Mix in some greens

If you are feeding your goldfish more packaged food, it is important that you maintain a proper quantity of green vegetables as they make the body of the food ingested and help in proper digestion.

Goldfish prefer oxygen weed Elodea crispa or Elodea canadanesis and duckweed.

The problem with feeding green food is however that some green plants may have parasites.

Alternative food like kale, Romaine lettuce, spinach, shelled green peas and broccoli can also be fed to the goldfish.

Frequency of feeding and amount

Goldfish are voracious eaters and you find yourself feeding them multiple times a day.

The goldfish also have primitive or rudimentary stomach and their intestine contributes to the moth breaking and assimilation of food which also leads the goldfish in a continuous hunt for food.

The frequency of food thus, also depends upon your portion.

Spread some food into the tank and watch the goldfish eat.

Notice how easily the food is consumed. If the fish keep the same interest in eating, keep feeding them until they lose interest in eating.

Typically, feed them 0.5% to 2% of their body weight in each serve.

If the food is fed mostly in the surface, goldfish can develop positive buoyancy disorder. Thus when it comes to feeding, it is better to mix floating and sinking pellets. For fancies, it is advisable them to keep mostly on sinking pellets.

Tank mates

Let’s face it. If you have an aquarium and if you have an aquarium large enough so that it sustains the natural growth of a goldfish, then you are always going to want to have another fish in it, isn’t it? I personally have seen people just chuck in various kinds of fish in the aquarium. You couldn’t be doing it more wrong if you just put fish that you like in the same tank. There are various factors that need to be considered, more so, in the case of goldfish.

The tankmates must not require tropical temperatures. Fish that grow in the same temperature and other water parameters as that of the goldfish can only be kept as tank mates.

Goldfish likes their personal space. Specially goldfish that have grown for a year or more by themselves like to be left alone in their tanks. And most often goldfish don’t actually need any company. This is evident when the goldfish starts showing intimidating behaviors like nipping, aggressive swimming, and restricting access to food at feeding times.

However, there are certain other species that can do well as the tank mates of goldfish. As said earlier, these species must thrive in the same temperature and water parameters as the goldfish and must strike this delicate balance of not being large enough to bully or harm the goldfish and be just large enough to hold their own when push comes to shove during feeding time.

Here are some of the best goldfish tank mates:

  • Other Goldfish

Well hello, of course. The best tank mate for a goldfish is another goldfish. But hold on, there are things you must consider even before you buy another goldfish and put it in a tank.

Your common comets must be kept with other comets. Comets, sarasa and shubunkin varieties have similar body types but have different coloration and can add character to your tank. Comets also grow well beyond a feet. And they require lots of room to swim around. Having other tank mates impeding it’s space will mean that your goldfish will have stunted growth and live shorter.

Fancies must be kept with other fancies. Fancies are slower than common goldfish and that can be a problem when feeding time comes.

If you have overly competitive fish, try to spread the food over the entire tank or mix floating and sinking food.

  • Zebra fish (Danio rerio)

These are smaller fish that swim in groups. Zebra fish max out at 2 inches of length making them considerably smaller than most goldfish.

They can be a good tank mates for both comets as well as fancies.

They come in various fin sizes and colours.

Don’t choose zebra fish that are too small or else they may just swim into the mouth of your goldfish.

Mixing up food targeted separately for both goldfish and zebra fish is advisable as it reduces competition for food.

  • Rosy barbs

Rosy barbs have the same water requirements as goldfish.

They grow to be 4 to 6 inches in length making them a suitable tank mate interms of size. They are not aggressive too.

Rosy barbs however live in schools, and should be kept in the schools of atleast 6.  

  • Weather loaches or Dojo Loaches

These fish also thrive in the sane environment as the goldfish.

These fish however, love burrowing and need a company if atleast 3.

Also, if you have goldfish along with loaches, you will need a pretty large tank as loaches themselves love large spaces on their own.

  • Apple snails and Nerite snails

When it comes to snails, non-tropical freshwater snails are very limited. But there are two species, the apple snails and the nerite snails that are good tank mates fir your goldfish.

Apple snails are larger and tough as nails. The goldfish may try to eat them but because of their hard shells, that task becomes nearly impossible. These eat plants and also share the bio load of the tank and their population is easy to control as they lay eggs outside water.

Nerite snails however are a bit more sensitive since they are caught from the wild. They can’t reproduce in freshwater but will lay small eggs that never hatch. The added benefit is that they eat a lot if algae.

  • Plecos

Species of plecos like rubbernose d bristlenose plecos are suitable tank mates for goldfish.

These spend most of their day eating algae from rocks and grass thus also helping keeping the tank clean too.

  • White cloud mountain minnows

These minnows share the same environment with goldfish as they are cold fish too.

These are also fast swimming fish which makes it easier for them to stay away from the goldfish.

These are schooling fish hence a group of 3 to 6should be added.

  • Some shrimp

Ghost shrimp are amicable additions to the tank and are small thus leaving proper space for goldfish without causing any harm.

Red cherry shrimp also serve as algae eater. 

Shrimps however will be devoured easily by goldfish if kept exposed. Hence, caves and decorations help keep them safe.

Goldfish diseases

Goldfish are remarkably strong fish and most if their diseases are related to poor living conditions. Infact, you may very rarely encounter a goldfish diseases if you maintain a proper water parameter and change and clean your water regularly.

But that is no guarantee that your goldfish will never be sick. If they do, you will be better off catching the symptoms early.

  • Your goldfish visits the surface more than usual:

This happens when the dissolved oxygen content in your tank is low. Thus the fish come to the surface and gasp in gulps of oxygen from the surface.

  • Loss of appetite and weight loss:

Goldfish are voracious eaters. So, if your goldfish refuses to eat along with noticable signs of weight loss, it may be a warning sign.

  • Goldfish lays at the bottom and shows little activity:

Goldfish are naturally roaming and foraging fish. But, incase of an infection or poor water quality they may just tend to lie on the bottom and show little activity.

  • Weird swim patterns:

If your fish is suffering from buoyancy problems related to swim bladder you may notice it swimming weirdly or even upside down.

Here is a simple list of diseases and infections that your goldfish may have and ways to treat them:

Ammonia poisoning

Perhaps the most common problem in a goldfish tank is ammonia poisoning. The new tanks have a higher probability if having ammonia poisoning because it requires a certain time for the natural nitrogen cycle to be established.

This can cause high levels of stress in goldfish and may end up in bacterial infection.

Symptoms and signs:

 Goldfish visiting the surface more than often gasping for breath.

 Red or inflamed gills

 Water may appear murky


 Checking the pH and the ammonia levels us a must.

 Also check the water temperature.

Don’t change the water in its entirety as it disturbs the nitrogen cycle and pH and temperature. 30% to 50% water change is advised. 

Clean the gravel properly and use high quality food.

Avoid overfeeding and overcrowding during feeding.

Test your water filtration unit regularly.


Symptoms and signs:

The abdomen region of the fish seems to be swollen.

Sometimes it causes the scales to stick.

Fish appears listless.

Loss of appetite.

Dropsy is fatal.


Take the fish out and quarantine them in a separate tank and take them to the vet.

Maintaining water quality is a must.

Cotton mouth:

This is a bacterial infection. And it mostly affects cold-water and tropical fish.

Usually starts with a pale area around the head and mouth.

It may then go on to mimic fungal infection by the growth of white or greyish white spots on the head of the goldfish.

These spots may turn yellow or brownish yellow with reddish tinge around the edges.

Bacteria generally affects the fish’s mouth, but lesions can appear on the back that looks like a saddle on the fish’s body. Some ways to treat this condition include a 30 percent to 50 percent water change with a siphon of the tank’s gravel. Aquarium salt can be used, but ensure that your fish can tolerate it (see below). You can use Furan 2, Melafix, or a vet-prescribed antibiotic.

In addition, you should remove the carbon from your tank’s filter during treatment. This infection is one of the reasons you need to use a quarantine tank.


It is a bacterial infection but is one of the most easily curable and preventable diseases in goldfish.

Poor quality of water, overcrowding, stress generated from noise pollution, fighting with ill-placed tank mates, mishandling, and very low temperature causes finrot.

Symptoms include split or ragged fins with often white edges to them. Fins may also have red streaks on them.


On the first day: change almost half the water in the tank and test the rest of the water.

Take 1 tablespoon of aquarium/kosher/pure rock/ sea salt and mix it with 10 gallons of water each.

If you are using Epson salt, mix 1 teaspoon per 10 gallons of water. And if you are using Melafix mix half teaspoon per 10 gallons but keep in mind the pH of the water is not more than 7.5.

Do not change the water quickly, take your time. Replace only 5% of water per 15 minutes and add water treatment to the water you add then after to remove ammonia and chlorine.

From the second to the 5th day:

Perform 20% water change per 15 minutes.

Add 1 tabkespoon of salt per 10 gallons of water

Before adding to the tank, don’t firget to dilute and mix thoroughly in a one gallon of tank water 

6th day:

Only water changes for the next 5 days.

11th day:

Repeat the entire treatment but with only salt.

If even after a month the signs remain, start the treatment again from day one.

Hole in the head

It is one of the most uncommon diseases in the goldfish. The causes to this disease can be attributed to a few different factors depending upon the situation.

Environmental factors and poor living conditions like in every other goldfish disease contribute here too.

Some researchers also believe, the carbons used in filtration units aids in this condition.

And perhaps the most scientifically backed theory of all, a parasite named Heximita that resides in the intestine of the goldfish causes hole in the head.

Symptoms include a small sore above the eye that later grows and penetrates through the outer layers of head inti a small hole. If left untreated, the small hole grows into a full-fledged tubular tunnel which ejects mucus and yellow fluid through it.


Maintain proper water parameters and do regular water check-ups. Start with 20% to 30% water changes every 3 days and clean the bottom of the tank or vacuum the gravel.

Add one tablespoon of salt per 10 gallons of water, dilute it with 1 gallon of tank water and add it to the remaining water in the tank.

Feed the fish vitamin enriched diet and be sure to clear out left over food.

Get the tank checked for Heximita.


This is the most common goldfish disease caused by a ciliated protozoan parasite.

It is caused by poor water quality, overcrowding and sudden change in temperature.

Ich usually targets fish that have been continually under stress and have low immunity.


Small white spots in it’s gill, body and fins.

Your goldfish starts to rub or itch against rocks and even tank surface.


When the protozoan parasite first infects the fish, it entrenches itself in a cyst. This cyst surrounding the parasite in it’s trophozoite form is unreachable by the medicines. Hence, the lifecycle of the parasite must be hastened in order for the treatment to begin.

The first thing to do is increase the temperature to 75 to 80 degree Fahrenheit. This hastens the life cycle of the parasite to 3 to 5 days. Do not increase the temperature 1 to 2 degrees per hour and let the temperature be for 10 days. The catch however is to keep continuing this treatment even when the spots start to vanish.

Or else, you can use salt treatment which is more budget friendly or else you can go for malachite green, formalin or chopper. The temperature of the water should be kept under control when medicines are used as high temperature in conjunction with medicines causes oxygen deficiency which can lead to death.

Swim Bladder Disease

This is another very common problem you may face in your pet keeping journey.

Swim bladder is a common feature in fresh water fish that helps them in floating and regulates buoyancy. These are basically air sacs that help the fish to dive down and come back to the surface again. So you can guess, if the swim bladder is deformed the fish will find such activities stressful.

There are various reasons as to what may cause trouble with the air sacs in a goldfish.

A sudden change in temperature leads to a thermal shock that leads to disorders in swim bladder.

Increase in Ammonia, nitrite and nitrate level causes capillaries leading into air sacs to dilate causing this problem.

Bullying from other tank mates also may lead to swim bladder disorders.

Most common cause of swim bladder disorder though is over feeding or diet lacking in fibres which leads to constipation and abdominal swelling impending the normal functioning of the swim bladder.

It is worth noting that the fancy goldfish are more susceptible to swim bladder than common ones because of their round body makeup.


The fish swim upside down or flip over.

Unable to dive downwards or float upwards.

List to one side.


Feed finely chopped, mushed, de skinned and steamed peas to the fish for 3 days.

Stop feeding anything else to your fish. This allows the distension in the abdomen region to settle down. Once, you see the distension going down slowly start to feed them again.


Over relying on pellets and flakes and processed food should be stopped.

Feed food balanced in protein and fibre and include veggies in food. Stop ivervrowding and choose the tank mates properly so as to ensure the goldfish do not face nipping and aggressive behaviour from the other fish.


Can I keep my goldfish in a bowl?

You can. But you shouldn’t. If you just got your small goldfish from the pet shop, you may tempted to think that you can keep them in a fishbowl as propagated by cartoons and pictures in newspapers. But Goldfish can grow more than a feet long depending upon the variety. Their growth depends on many things and one of the most important things out of them is: their living space. The living space can curtail the growth of the goldfish meaning that goldfish that are kept in smaller bowls or aquariums have stunted growth and shorter lives.

How big aquarium do I need?

Look, there is no one sentence answer to this or one precise mathematical data or formula to calculate the size of the aquarium needed. And the size of the tank also depends upon how many goldfish are you keeping, and what stage in the life span is the goldfish in. Make sure you get younger and smaller goldfish from the pet shop and get as large an aquarium that fits your budget and living space. Generally, the size of the aquarium should be 4 times the maximum length the goldfish can grow to. But start with atleast 2 to 2.5 feet long aquarium or 75 gallon tank.

Can I use tap water to fill up the tank?

Tap water definitely is the most feasible thing to fill up your aquarium with. But keep in mind that tap water consists of chlorine and it’s stubborn derivative chloramine. These can hurt the fish causing various kinds of discomfort. So, before you chuck in tap water in the aquarium make sure you treat the water with water conditioner or dechlorinator beforehand. You can easily buy these products from your nearest pet shop and these are not expensive too.

Why do goldfish look different in each tank I see?

Goldfish have only one species the Carrasius auratus but they have several varieties. These goldfish from different varieties look different. Among the common goldfish the comets have a longer, comparatively slender body and pointy tail and the shubunkin are blue and speckled and robust.

The fancy varieties have rounder bodies, longer flowing fins and often deformed eyes and heads. They grow to a smaller size than the common goldfish and are slow to swim and manoeuvre.

Why does my aquarium make noise? Can I turn it off at night?

Generally the air pumps used in the underground water filters make a bit of noise as expected and that maybe a bit pain in the ears if you have an aquarium in your bedroom.

But turning off the aquarium systems at night isn’t a good idea. The water filter in the aquariums have many useful bacteria that help in the cleaning if the water. In the absence of the electricity supply to the air pump, these bacteria cannot be supplied with oxygen rich air which in turn leads to the water being more polluted.

What do I feed my goldfish and how frequently?

There are various goldfish specific food you can buy in the pet shops. These may include the manufactured, readymade and packaged dry foods, frozen food that come in pellets, flakes and gel form. However, you cannot simply rely upon these manufactured foods all the time. Over relying on such food items may cause constipation and abdominal swelling in the goldfish as they lack proper moisture and water content. Also, live food must be included too.

Goldfish are voracious eaters and they eat like there is no tomorrow. The frequency of feeding them. Depends upon various factors like are you breeding them or just sustaining them. Or are you looking for growth in the fish? It also depends upon the season. Simply put, spread some food in the tank and watch the goldfish gobble up the food. Keep feeding them until they start showing little to no interest in further eating.

How long do goldfish live?

Once again, the environment plays a huge role. If you are determined in being an asshole despite us warning several times before and keep. The fish in a fish bowl, goldfish will live no more than 5 years.

In a properly kept aquarium with balanced diet, they can live slightly more than a decade. And if you are one if those people with a pond in your backyard, they can easily live upto 20 plus years.

How do I know if my goldfish is sick?

There are many tell-tale signs that a goldfish exhibits when it is in discomfort. . You may see physical signs like spots on the fins and gills to reddish flares on the fins. You may notice small dot like thing above the eye on the head of the fish which may turn out to be a hole. The goldfish may also exhibit symptoms like swimming upside down or scratching on rocks or even on the tank surface or showing lack of appetite. Swim bladder related problems that are one of the most common problems to have in goldfish may lead the fish to stay at the bottom and show little activity.


 You can have your reasons to keep a goldfish aquarium in your home, from visual addition to your living room to having genuine pets to astrology related reason but goldfish should be well taken care of. Goldfish are sturdy and tough fish and if kept properly with proper water parameters maintained, you may encounter very little problems with keeping these floating pets. But there may be many things you have to consider before you embark on your journey of fish keeping. And as you have read and researched by now, not everything is as simple and straight forward as you may think. But that is no reason to be dissuaded, as we can say from experience, with time everything gets easier and more familiar.

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