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.

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