Goldfish Care [Diet, Tank Setup, Breeding, Etc.]

Goldfish Care [Diet, Tank Setup, Breeding, Etc.]


Goldfish are favorites among aquarists due to their colorful appearance and peaceful nature.

They’re often the first pet for many fishkeepers because of their easy maintenance.

Let’s learn about these beautiful fish in more detail.

Goldfish Species Overview

The common goldfish is a freshwater fish belonging to the Cyprinidae family of order Cypriniformes.

Native to East Asia, goldfish is a relatively small member of the carp family and is closely related to other ornamental fish like koi.

Initially, goldfish were kept and bred in China for over a thousand years.

But goldfish can now be found worldwide in aquariums, ornamental pools, and in the wild.

Goldfish inhabit slow-moving waters like ponds, streams, lakes, and rivers in their natural environment.

They even thrive in muddy waters with low oxygen levels in the wild.


Beautiful goldfish

Goldfish are slender, long-bodied fish.

They’ve curved dorsal fins laden with a stripe across their belly with two sets of paired fins, namely pectoral and pelvic fins.

Goldfish have large eyes with no scales on their head. They also lack the barbels on the upper jaw.

Besides, goldfish have pharyngeal teeth in their throats for chewing the food.

Goldfish are gold, olive green, or even creamy white in color in the wild.

On the contrary, they can be found in different bright colors such as orange, yellow, red, brown, grey, or black in captivity due to selective breeding.

Names of Species

Goldfish are found in various colors, sizes, patterns, and body shapes.

They’re one of the first fish bred in captivity over a thousand years ago.

There are over 200 varieties of goldfish created through extensive selective breeding.

Given below are the various types of goldfish as per their appearance.

Slim-bodied/streamlined with a single tailCommon Goldfish, Comet Goldfish, Shubunkin
Streamlined with a double tailWakin Goldfish, Jikin Goldfish, Watonai Goldfish
Egg-shaped with a dorsal finFantail Goldfish, Ryukin Goldfish, Veiltail Goldfish, Telescope Eye, Oranda, Butterfly Tail Goldfish, Tosakin Goldfish, Pearlscale
Egg-shaped without a dorsal finCelestial Eye Goldfish, Bubble Eye, Lionhead, Ranchu Goldfish, Pom Pom Goldfish, Phoenix, Tamasaba
MiscellaneousFroghead Goldfish, Lionchu, Nymph Goldfish


Goldfish have a reasonably long lifespan. They can live up to 10 to 15 years if housed in proper water conditions and fed a varied diet.

Goldfish can barely live for a year if kept in a small bowl.

So housing goldfish in a large tank and meeting their behavioral and physiological needs is crucial to increasing their longevity.

Average Size

Goldfish vary in size depending on their living conditions.

They tend to grow up to 1 inch (2.5 cm) to 2 inches (5.1 cm) long in a small tank.

However, goldfish may grow large and reach up to 6 inches (15 cm) when kept in big aquariums.

In outdoor ponds and in the wild, goldfish grow extensively and reach up to 12 to 19 inches (30 to 48 cm) in length.

Goldfish Tank Setup

Goldfish tank

Goldfish getting sold in tiny bowls is a common sight.

Hence, many people often think that they can keep goldfish in a small tank or bowl without any equipment.

However, it’s not the ideal way to keep goldfish, especially if you wish to enjoy their company for a decade or so.

Let’s understand the tank requirements of goldfish in more detail.

Tank Size

The size of the tank depends on the goldfish species and the number of fish you need to house.

An average goldfish can grow about 4 to 6 inches in length, while some larger ones can grow as long as 12 inches.

So it’s always better to invest in a larger tank.

To begin with, each goldfish needs at least 10 gallons of water. Hence, the minimum tank size for a common goldfish is 20-gallons.

If you have a fancy goldfish, you will need a 20-gallon tank for a single fish.

You should add at least 10 gallons of water for every new goldfish added to the tank.

A tank holding 30 to 55 gallons of water is required for a slim-bodied goldfish.

Some of the guidelines you can keep in mind while setting up a goldfish tank are:

  • 1 gallon per 1 inch of goldfish,
  • 1 square foot of aquarium’s surface area for every inch of goldfish,
  • 10 to 30 gallons of water per fancy goldfish.

Tank Equipment And Decorations

The most important thing for goldfish is to have a large tank with ample space to swim freely.

The water movement in the tank needs to be gentle since they’re used to living in slow-moving waters in their natural habitat.

Goldfish tend to scavenge for food at the tank’s bottom. So the gravel needs to be small, making it easier for them to move.

Goldfish have been known to jump out of their tanks. Hence, the tank needs to be appropriately covered to avoid any mishap.

Given below are the items required in a goldfish tank:

  • Substrate,
  • Efficient filter,
  • Live Plants,
  • Aquarium Hood Cover,
  • Bubble Walls to increase the oxygen flow in your fish tank, and
  • Decoration such as caves, rocks, driftwood, etc.

Goldfish Care

Healthy goldfish

Caring for goldfish is easy as they’re hardy.

Goldfish can survive a wide variety of living conditions, making them one of the best fish for a novice aquarist.

Let’s now discuss how to take proper care of your goldfish.


The goldfish diet primarily consists of algae growing on the rocks and logs, floating on the water surface, and decaying plant matter in the wild.

Goldfish also feed on small fish, tiny crustaceans, aquatic insects, and mosquito larvae as and when they’re available.

In captivity, goldfish need a varied diet that suits their dietary requirements. They require a diet rich in carbohydrates.

Since goldfish are notorious for eating, they accept food at any point and at all aquarium levels.

So feeding goldfish isn’t a difficult task.

Store-bought flakes and pellets suitable for goldfish can be a convenient staple food for goldfish.

You can supplement these with veggies such as spinach, kale, lettuce, boiled peas with shelled removed, cooked vegetables such as zucchini, cucumber, etc.

Fruits such as chopped bananas and grapes are also suitable for goldfish.

To meet their protein requirements, you can occasionally treat your goldfish with live and frozen food such as daphnia, brine shrimp, micro worms, blood worms, cricket, etc.

The only thing to remember while feeding goldfish is not to overfeed.

Overfeeding can lead to indigestion, bloating, constipation, and swim bladder disorder.

You can feed goldfish twice a day. Feed only the quantity that they can consume in about 3 minutes.

Water Parameters

Goldfish are hardy species and are tolerant of a beginner aquarist’s mistakes in maintaining the water quality.

However, rapid and drastic changes in the water chemistry or temperature can be harmful to their well-being, if not fatal.

Goldfish can tolerate a wide range of pH, provided your KH level is high enough to stabilize the pH levels.

Goldfish are coldwater fish, and unlike tropical fish, they don’t need warm water to thrive.

The ideal water parameters for goldfish are:

Water Temperature68°F to 72°F (20°C to 22°C)
pH level6.0 to 8.0
General Hardness (GH)150 ppm
Carbonate Hardness (KH)70 ppm to 140 ppm
Ammonia< 0.1 ppm
Nitrate< 50 ppm (<110 ppm tolerance)
Nitrite< 0.2 ppm

Tank Maintenance

Goldfish are messier than most other aquarium fish. They dirty the tank very quickly.

So tank maintenance is a regular activity for any goldfish owner.

Performing regular water changes is one way of keeping the tank clean.

You can perform weekly partial water changes of 10% for new tanks and monthly 25% water changes for established tanks.

You should also regularly clean the filter, substrate, and other decorative items in the tank.

An algae scrubber, water conditioner, and siphon supplies can make tank maintenance easier.

You can use a gravel siphon to remove the debris and other residues from the bottom of the tank.

A liquid-based water quality test kit is recommended to maintain stable water chemistry.

Common Diseases

Goldfish are pretty hardy fish. Their hardiness helps to keep diseases at bay.

However, they can succumb to common freshwater diseases like fungal, parasitic, and bacterial infections.

Some of the common goldfish diseases are:

  • White Spot Disease (Ich),
  • Fin Rot,
  • Gold Dust Disease (Velvet),
  • Fish Lice (Argulus),
  • Swim Bladder Disease,
  • Dropsy,
  • Polycystic Kidney Disease,
  • Popeye or Cloudy Eyes,
  • Anchor Worm (Lernaea),
  • Red Streaks on Skin and Fins, etc.

Goldfish Behavior and Temperament

Goldfish are social and playful creatures that generally don’t exhibit aggressive behavior.

They usually don’t harm their tankmates, nor do the male goldfish harm the females during breeding.

The only time when goldfish can become aggressive is while competing for food.

They can eat all the food in the tank before the slow-moving or timid fish reach the food.

Goldfish can also become territorial under unfavorable conditions like cramped space due to overcrowding, unsuitable tankmates, unfavorable water parameters, stress, or sickness.

In terms of behavior, goldfish like to explore their environment.

You can see them darting all across the tank instead of gathering in one area of the tank.

Goldfish Tankmates

Goldfish with tankmates

Goldfish are communal, social fish that enjoy the company of other fish.

You need to house similar-sized and similar temperament fish with goldfish.

The water parameters should also be considered as goldfish is a coldwater fish and can thrive without a heater.

Some of the compatible tankmates for goldfish are:

  • White Cloud Mountain Minnows,
  • Longfin Rosy Barbs,
  • Japanese Rice Fish,
  • Bristlenose Plecos,
  • Giant Danios,
  • Hillstream Loaches,
  • Tetras such as Black Skirt, Bloodfin tetras, etc.,
  • Apple Snails,
  • Shrimp such as Bamboo shrimp, Ghost shrimp, etc.
  • Scissortail Rasboras,
  • Zebra Danios,
  • Rosy Barbs, etc.

While goldfish are compatible with numerous fish species, you should avoid keeping certain aggressive fish.

You should also avoid housing goldfish with small and spiny fish as their spines can get stuck in the gill plates of goldfish while attempting to swallow them.

The fish species that you should avoid housing with goldfish are:

Goldfish Breeding

Goldfish are oviparous, meaning the female goldfish lay eggs for the males to fertilize.

In the wild, breeding usually happens in the spring season.

You can follow the below instructions to breed goldfish in captivity.

  1. Start with setting up a breeding tank of at least 20-gallons in size. Stock the tank bottom with gravel and a variety of aquatic plants.
  2. The ideal temperature for spawning is between 70ºF to 75º F. You need to increase the temperature slowly until spawning begins.
  3. You can place a spawning mat in the tank. The mat can catch the eggs and can make them easier to handle.
  4. Then, put the male and female goldfish in the tank together. Condition the pair by feeding them live food such as brine shrimp and worms.
  5. The pair will start chasing one another when the female goldfish is ready to spawn.
  6. Spawning lasts for a few hours, with the female goldfish laying around 1000 eggs. The male goldfish then fertilize the eggs.
  7. It takes around a week for the eggs to hatch. Not all eggs hatch as some don’t develop while others don’t get fertilized.
  8. In the first couple of weeks, you can feed fry food, infusoria, baby brine shrimp, and some algae to the newly born fry. After that, you can feed them slightly larger food like mosquito larvae and daphnia.
  9. Finally, you can transfer the goldfish fry into the main tank once they’re over an inch long.

Frequently Asked Questions

Can Guppies Live With Goldfish?

Guppies and goldfish can live together in one tank. However, it is not advisable to keep guppies and goldfish together. Here are some reasons why you shouldn’t put these two species of fish together:

  1. Big goldfish may eat guppies.
  2. Guppies are known to nibble on the fins of goldfish.
  3. The temperature in the tank is different for guppies and goldfish.
  4. Dietary needs are different for goldfish and guppies.
  5. Water pH levels need to be different for goldfish and guppies.
  6. Goldfish and guppies can fall ill.

Can Neon Tetras Live With Goldfish?

Neon tetras cannot live with Goldfish because of the following reasons:

  1. Tetras thrive in a warm environment while Goldfish like a cooler aquarium. Tetras thrive at 28-30 degrees celsius, and Goldfish do best at 23-24 degrees celsius.
  2. Goldfish can eat neon tetras.
  3. Goldfish produce a great deal of waste and require frequent tank maintenance, while tetras are sensitive to water changes and do best in an established tank.
  4. Neon Tetras can pass on diseases to goldfish.
  5. Both have different social habits.

Can Goldfish Live with Bettas?

Goldfish cannot live with bettas because of the following reasons:

  1. The habitat needs of goldfish and bettas differ. As tropical fish, bettas need warm water while goldfish are cold-water fish.
  2. They have different temperaments. Goldfish are easygoing and friendly, while betta fish are aggressive and short-tempered.
  3. Goldfish and bettas have different nutritional requirements. Goldfish are omnivorous, while bettas are carnivores.
  4. Goldfish produce excessive ammonia-rich waste and dirty the tank. So, they need a strong filter or frequent water changes. The cleaner betta fish do not like frequent water changes nor strong filter currents.

Do Goldfish Need Filters?

Goldfish do not need filters. Goldfish tend to adapt to their habitat. So, they can survive without filters. However, goldfish create a lot of waste. Without a filter, the waste will pollute the water and increase ammonia levels. This will stress the goldfish, and they can die in 2 or 3 years.

Can Goldfish Live In Tap Water?

Goldfish cannot live in untreated tap water for too long. Untreated Tap water usually has high concentrations of chlorine and heavy metals that poison the fish and kill it. However, neutralized tap water that is free from chlorine-based disinfectants and heavy metals is suitable for goldfish.

Can Goldfish Live Alone?

Goldfish can live alone. Even when they are kept alone, they live a long and healthy life if they get good nutrition and a clean environment. However, it’s a good idea to keep goldfish with other fish. They will benefit from the interaction and companionship and will live happier lives.

When Do Goldfish Mate?

Goldfish mate when they are around three years old, and the water temperature is warm. Technically, the mating process is called spawning. They spawn by chasing each other until the female goldfish releases her eggs. The male goldfish then releases his milt or sperm to fertilize the eggs.

What Do Goldfish Eat In The Wild?

Goldfish are omnivores that feed on both plant and animal matter in their natural habitats. They usually eat aquatic plants, algae, small insects, tadpoles, plankton, and small crustaceans. If they find small fish, they will eat it. They will eat almost anything that fits their mouths.

Do Goldfish Eat Snails?

Goldfish do eat snails. Goldfish eat everything that fits in their mouth. So, if goldfish find a small snail and are hungry, they will eat it. Bigger snails are safe from goldfish as they won’t fit in goldfish’s mouth. However, goldfish will eat dead snails regardless of their size.

Do Goldfish Eat Plants?

Goldfish eat plants. However, they do not eat certain live plants like Anubias, Java Fern, and Anacharis as they are difficult to nibble. Live plants are recommended for goldfish aquarium as they help maintain the water’s oxygen levels by removing the ammonia and carbon dioxide.

Can Goldfish Eat Bread?

Goldfish can eat bread. However, it’s not advisable to feed bread to goldfish. Bread contains yeast and gluten, which are difficult to digest for goldfish. Eating bread causes indigestion, constipation, and swim bladder disorder in goldfish. Also, bread doesn’t have any nutritional value.

Can Goldfish Eat Chocolate?

Chocolate is not a recommended food for fish of any type including goldfish. The diet of goldfish should mainly consist of fish flakes or pellets.

Why Do Goldfish Kiss?

Goldfish kiss because they are either flirting or threatening each other. Kissing is usually an act of aggression, where the goldfish try to size up each other. Male goldfish may also kiss females during the mating ritual, where the male pursues the female until she gives in and releases her eggs.

Can Goldfish Regrow Scales?

Goldfish regrow scales that have fallen off due to nipping or infection. Making sure that the water is clean and that there are places for your goldfish to hide from other fish is important to reduce scale loss due to nipping.

Can Goldfish Lose Their Color?

Goldfish can lose their color. Goldfish are a type of carp. Their golden color is due to selective breeding. Because gold is not their natural color, goldfish are susceptible to color loss if anything in their life changes. The main reasons for goldfish to lose their color are:

Do Goldfish Poop and Pee?

Goldfish poop and pee. There is a tiny opening under the goldfish called “vent” in the area between the abdomen and the tail fin. This is from where poop is released in the form of small dark-colored pebbles. And goldfish pee by urinating through the gill.

Can Goldfish Bite?

Goldfish can bite. They have small teeth in their mouths using which they can nibble on you. But you won’t feel much pain even if your goldfish bites you. This is because goldfish don’t bite the same way other animals bite.

Do Goldfish Eat Each Other?

Goldfish do eat smaller goldfish if kept in the same tank. This is also the case with other popular types of fish, such as guppies and catfish.

Do Goldfish Eat Other Fish?

It depends. Goldfish aren’t predatorial by nature. However, they will eat anything that fits their mouth. If they come across small fish while browsing for food, they will most likely eat it. Goldfish also attack their tank mates if food is scarce or their living conditions are less than ideal.

Why Do Goldfish Float?

Goldfish float if they are suffering from swim bladder disorder. A deformed or dysfunctional swim bladder, improper diet, and bacterial infections due to unhygienic water conditions cause swim bladder disorder. Also, excess air in the swim bladder affects buoyancy and makes the goldfish float.

Can Goldfish Live In Ponds?

Goldfish can live in ponds. A pond is ideal for goldfish because it closely resembles their natural habitat. Goldfish will grow more and live longer in a pond than it would in a tank. However, goldfish need stable temperature conditions, sunlight, and clean water to thrive in a pond.

Can Goldfish Live In Dirty Water?

Goldfish can live in dirty water only for a short period of time. However, it will die if you keep it in dirty water for too long. Dirty water will shorten the life span of your goldfish. Just like all other species, goldfish need healthy living conditions to survive and thrive.

Why Do Goldfish Keep Chewing?

Goldfish keep chewing to grind their food properly before swallowing it. They chew the food with their pharyngeal teeth, and the resulting crushing action produces the clicking sounds that you hear. Since goldfish keep on grazing constantly, it looks like they are chewing their food continuously.

Can Goldfish Freeze and Come Back to Life?

Goldfish cannot freeze and come back to life. They will die. This has to do with the biological makeup of their cells. Their cells are made up of thin membranes that when frozen, will expand and rupture causing the goldfish to die.

Why Do Goldfish Die So Fast?

Goldfish die quickly if they are weak, unhealthy, or ill. Even Healthy goldfish die early if you keep them in a small or overcrowded tank. Sudden changes in water chemistry, poor filtration, improper feeding, and bullying by aggressive tank mates are the other factors that kill goldfish.

Can Goldfish Drown?

Goldfish cannot drown, but it can suffocate underwater. It can suffocate because of insufficient oxygenated water, damaged gills, or because of it getting stuck underwater. For goldfish to breathe underwater it needs to move so that water can circulate over its gills and it can take-in the oxygen from the water. Just like all fish, goldfish too; need oxygen to survive, and if the water it’s in runs out of oxygen, then it will die. For example, if you leave a goldfish in a small bowl it will eventually run out of oxygen if there is no working filter connected.

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