Do Goldfish Eat Other Fish? (Why And When They Attack Other Fish)

Image of goldfish swimming together

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.

Let us try to understand more about why and when goldfish eat other fish and how to prevent them from doing so.

Feeding Habits Of Goldfish

Goldfish are omnivores that eat both plants and animals.

In the wild, they feed on algae, aquatic plants, invertebrates, insect larvae, worms, snails, and small fish.

Goldfish in captivity thrive on a varied diet. Most goldfish owners feed them a basic diet of goldfish flakes and pellets.

While this helps them survive, it is usually not enough for the fish to grow big. They also need natural and live food.

Shelled peas, leafy greens like spinach and kale, cooked rice, corn, zucchini, cucumbers are some of the foods that you can feed your goldfish.

You can also give fruits like oranges and watermelon to your goldfish.

Live natural treats like mealworms, crickets, bloodworms, brine shrimp, and daphnia are also good for goldfish.

These rich sources of protein will help your fish grow faster.

Goldfish have an enormous appetite, and they are constantly on the lookout for food.

They tend to constantly graze and snack on what they can find.

They won’t care even if it is an insect or smaller fish. If it fits their mouth, they will eat it.

Do Goldfish Eat Smaller Fish?

Have you noticed how goldfish always look hungry?

Once they associate your presence with food, they will even wiggle their fins and tails and do a hungry dance whenever they see you.

Goldfish search for food all the time and eat anything that fits their mouth, which can prove dangerous for smaller fish.

Also, when it comes to food, goldfish are not choosy.

It doesn’t matter even if it is a baby goldfish. If they can catch it, they will certainly eat it.

Adult goldfish even graze on goldfish eggs.

So, any fish fry in the tank, including baby goldfish, are at risk until they reach a size where they are too big to be eaten.

Goldfish will also eat other species of adult fish that fit their mouths. For instance, guppies are small enough to be eaten by goldfish.

Guppy fry are extremely vulnerable as they are tasty bite-size morsels for goldfish.

So, it is unwise to keep goldfish and guppies in the same tank unless the guppies are too big for the goldfish to eat.

Guppy fry will not survive unless you separate them from the tank as soon as they are born.

When Do Goldfish Attack Other Fish?

Goldfish are generally good-natured and friendly. They enjoy and benefit from companionship.

Most of them like to interact with other goldfish and the rest of their tank mates. Single goldfish will also do just fine.

However, experts advise keeping goldfish in pairs or with other fish as they greatly benefit from the company.

Nonetheless, goldfish can become aggressive and attack other fish in certain circumstances.

If you observe bullying and aggression in your aquarium, promptly find and address the root cause of the problem.

Your pets will be stressed if you leave them unattended, and the harmony of the tank will be disrupted.

Check for the following problems if your goldfish seems to be bullying others.


Just like all fish, goldfish also need plenty of space to swim. Some goldfish can become very big.

So, the tank should be big enough to accommodate their needs.

Since goldfish produce a lot of waste, it should also have enough water to dilute it.

When space becomes a constraint, goldfish will attack other fish and show a territorial behavior.

Prevent this problem by getting a bigger tank or moving some of the fish to a new tank.

A 3-feet long tank that holds 20 gallons of water is usually enough for a single goldfish.

However, if you plan on keeping more than one goldfish, you should add ten extra gallons of water per fish.

Scarcity Of Food

Did you know that goldfish do not have stomachs?

They have a basic digestive system that absorbs essential nutrients and eliminates most of the food as waste.

So, they are always hungry and need regular feed to stay healthy. Goldfish always search for food and eat all the time.

A well-fed goldfish will have a calm disposition. However, it can become aggressive and hostile when food is scarce.

It may even bite its tank mates and chase them.

Prevent this problem by following a strict feeding schedule every day and keeping the fish content with enough food.

Make sure that the other inmates of the tank do not compete with the goldfish for food, and it will not be hostile towards them.

Mating Rituals

Sometimes, what you perceive as aggressive behavior may simply be the mating ritual of your goldfish.

During the mating season, goldfish males will chase the female around the tank until the female is exhausted and releases her eggs. This is normal behavior.

However, if there is more than one pair of goldfish in the tank, they may fight over mates.

To avoid this problem, keep fish of the same gender together or just one pair.

You can also separate the male during the breeding season to prevent this issue.

Dirty Water

Goldfish are sensitive to changes in water quality.

Since they produce a lot of waste, it is even more important to filter and clean the water regularly.

Ignoring water quality problems will create an unhealthy living environment for your goldfish.

It can also make your pet aggressive and prompt it to act out against its companions in the tank.

It is normal for a goldfish to eat any small fish that comes near it.

However, if your goldfish is hostile and attacks big fish, it may be caused by any of the above reasons.

Frequently Asked Questions

Do goldfish eat dead fish? Goldfish will eat almost anything that fits its mouth. So, it can and will eat dead and decomposing fish in the tank. Since this is not an ideal food, take care to remove any dead remains from the aquarium as soon as you find it. Nevertheless, goldfish will not usually chase and attack other live fish for food.

Which other fish are goldfish likely to eat? It is unwise to keep any fish that is smaller than a goldfish’s mouth in the same tank. Consider the maximum size that your goldfish can grow to when choosing its tank mates. Avoid keeping guppies, tetras, and other small fish in the same tank as goldfish. Small fish like the cory catfish are also unsuitable tank mates. Their small size can cause the goldfish to catch and eat them. However, when it does, their spines can fatally injure your goldfish.

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