Are Goldfish Aggressive? How to Stop Your Goldfish Aggression

Are Goldfish Aggressive? You’ve found the ideal article if you’ve been wondering if goldfish are hostile. You’ll discover not just whether or not goldfish are aggressive, but also what provokes violence, how to stop aggression, how to recognize when a fish is a victim of aggression, and much more.

Are Goldfish Aggressive?

Consequently, to answer the question, goldfish are often calm fish. When antagonism does happen, it’s usually because of issues with the tank or other tank mates. But generally speaking, you shouldn’t have any issues putting them in a tank with other fish.

A limitation to that is keeping them with smaller fish. A goldfish’s likelihood of bullying smaller fish increases if it is present in their vicinity (or, if they can fit in their mouth, eat them).

Are Goldfish Aggressive?

Are Goldfish Territorial?

If goldfish have territories, that is another question you could have. Fish that are territorial are considerably more likely to try to act violently to defend their territory. Fortunately, your goldfish shouldn’t be aggressive or hostile toward other fish as long as the tank is large enough.

Having said that, try introducing all of your goldfish at once for optimal results (but not too quickly or the tank won’t be able to handle it). Six weeks is usually a fair length of time.

This will lessen the likelihood that they will claim a certain region of the tank as their own.

Why Does Aggression Occur In Goldfish?

You now understand that hostility in goldfish is rather uncommon. That doesn’t mean it never does, though. And figuring out the root of the hostility in goldfish can help you discover a way to stop it!

Competing For Food

Competing for food is one of the most frequent reasons why goldfish become aggressive. All fish, even goldfish, have a lot of guts. They may see other fish as a danger and make an effort to fend them off if they are trying to take their food.

When it only happens around feeding time, you can quickly determine if this is the aggressiveness you’re dealing with. However, as you’ll discover later, there are several methods to prevent this aggressiveness from occurring.

When They’re Mating

The likelihood of aggressiveness will also rise during mating. The male fish will act violently toward any rivals, and it can even appear that they are acting aggressively toward the ladies.

After certain conditions are satisfied in the tank, mating aggressiveness is far more likely to happen. For instance, you may have been feeding them more often or the tank’s temperature may have risen to the ideal level for breeding. (68-74°F)

And occasionally, even a big enough water change might cause your goldfish to exhibit mating behavior. In any event, male goldfish will have breeding stars on their front fins and gills if you look at them closely. This is a surefire indicator that they are ready to reproduce.

Slow Swimmer And Fast Swimmers Are In The Same Tank

Aggression can occur when fast and slow swimmers are placed in the same tank. There are two distinct body kinds for goldfish, so keep that in mind while choosing which one to purchase. While the other is more egg-shaped, one kind has a more streamlined body.

While mixing these fish in a tank typically poses no issues, occasionally the quicker swimmers will pick on the slower swimmers, biting their tails and any other vulnerable body parts.

Fish with long, flowing fins, body components that protrude more than they should, and, of course, fish with bulbous bodies are some that are more likely to be bullied.

The Tank Is Overcrowded

This is also another of the most typical reasons why goldfish become aggressive. The majority of people frequently overcrowd goldfish in tanks that aren’t quite big enough for them because they are unaware of how much room they require.

To put it into perspective, in order to provide your fish ample horizontal swimming room, your tank should be at least 3 feet long. Additionally, you need 20 gallons for your first goldfish and an extra 10 gallons for each successive goldfish.

As you can see, this is a substantial amount of room, and if you don’t have it, the likelihood of hostility in goldfish will rise.

Why Does Aggression Occur In Goldfish

A Fish Is Sick

This is not a characteristic of goldfish alone; rather, it is a trait shared by all fish.

However, if your goldfish is going black, it might be a sign of something else completely. Learn more about it here! When one fish becomes unwell, the others start to attack, mistreat, or even kill them. There is a universal agreement even though the exact cause is unknown.

The healthy fish are thought to see the ill fish as a danger. Not only do they run the risk of attracting predators, but they also run the risk of spreading disease. So, in an effort to improve their own chances of surviving, they strive to exclude them from the group.


Sometimes, it’s just the personality of your goldfish. There may not be much you can do to change their innate aggressiveness. The “alpha” man or “alpha” female will typically exhibit these aggressive characteristics.

The only true answer if you realize they’re going out of control is to transfer them to another tank. Even though most fish are calm, if this makes you dislike goldfish, simply keep in mind that this may happen with any kind of fish.

They’re Territorial

When territorial, goldfish can occasionally become hostile. Even while it doesn’t happen as frequently in this kind of fish, it does happen. The majority of the time, it occurs when new fish are added to the tank with them.

When a new fish is first introduced and the goldfish in the tank already have a hierarchy established, it is far more likely to occur. However, it should subside after approximately a month.

There Are Too Many Males

In your fish tank, aggressiveness will frequently result if there are too many males and not enough females. Although this won’t be like other types of hostility, it will nonetheless result in a lot of harassment of women.

Additionally, the males may start to fight one another, which might ultimately result in one of them suffering a catastrophic injury. Therefore, while you’re filling your tank, be sure to include the appropriate ratio of males and females.

How Can You Tell When Aggression Is Occurring?

You can tell if aggressiveness is present in your tank in a number of different ways. Here are a few of the most frequent indicators of violence.

One Of The Fish Is Injured

When one or more fish in the tank are hurt, it is one of the most obvious signals that aggressiveness is taking place there. These wounds will often be on their fins and tail, however any part of their body might be hurt.

Just be sure the harm is coming from a fellow tankmate and not from a sickness or a sharp object in the tank.

Fish Are Scattered

Additionally, you can see fish in the aquarium who are being bullied start to conceal themselves much more. They could attempt to hide behind any decorations or plants you have in your aquarium, or they might look for a corner to lean against.

Your goldfish may be hiding, but that doesn’t always indicate they’re being bullied. They also hide when they feel unwell or when they feel frightened (like in a new tank).

Unliving Fish

A dead fish is one of the most obvious indicators of bullying, especially when other indicators have previously been noticed. This is especially true if the fish has injuries.

Find out precisely which fish is being aggressive and get rid of them from the tank if you see a dead fish there.

How Can You Tell When Aggression Is Occurring?

How To Tell If It’s Bullying Or Not?

Bullying may often be inferred from how goldfish interact with one another. Fortunately, there are a few universal signals if you’re unsure whether they’re bullying one another or not.

The warning indications include swimming around one another as opposed to going after or into one another.

You could also observe your goldfish coming together before veering apart, rather than two goldfish pursuing each other.

What Should You Do When You Notice Aggression In Your Tank?

Fortunately, there are several things you can do to stop aggression and ensure that all of your fish are content if one of your goldfish is acting aggressively. Here are a few brief pointers.

Make Sure The Tank Is Adequate.

First and first, you need to confirm that your tank is big enough to accommodate all of the goldfish you intend to maintain. The remaining procedures might not even function if the tank is too full.

Keep in mind that your first goldfish will require 20 gallons on its own, and each new goldfish will require an extra 10 gallons.

Put The Bully Away

The bully could also benefit from being taken out of the tank and placed somewhere else. If that doesn’t work, another option is to use a tank divider to keep them away from the other fish.

Sometimes even removing them from the situation for a little while may stop them from acting violently. This is particularly true if they see a certain region of the tank as their domain or if they believe they are the dominant fish.

Before adding them back, it’s a wonderful idea to shift the tank around. They’ll feel as though they’re in a new territory when you move the tank, which will make them much less inclined to behave aggressively.

Separate The Aggressor While They Are Feeding

Separating a fish from the other fish might be a good idea if it behaves aggressively just when it is hungry. Either placing them in a floating box or catching them in a big net will work for this.

You may start feeding them and the other fish without worrying about hostility once they are secure within the net.

If it doesn’t work, you can always try distributing the food evenly across the tank to make sure everyone is getting the same amount.

Make sure your goldfish have adequate food during the day at this time as well. Naturally, if they aren’t receiving enough food, they will act aggressively around it.

Your goldfish has to be fed for two minutes, two to three times every day. Anything left in the tank beyond that period should be disposed of.

Make Sure The Water Is of Good Quality.

All of the fish in your aquarium will become stressed out if the water quality is poor. They are far more inclined to respond violently toward one another when they are under stress.

Making sure you’re utilizing a filter, doing routine water changes, and eliminating any trash or debris that accumulates in the tank are some strategies to ensure the water quality is good.

Include Plants And Coverings

Including plants and hiding spots in the tank is a fantastic additional strategy to stop violence from happening. By doing this, you’ll not only provide any more submissive fish a place to hide, but you’ll also create a lot of places that will obscure the aggressors’ lines of sight, decreasing the likelihood that they’ll pursue.

Avoid Goldfish That Are Known To Be Aggressive.

Additionally, keep away from goldfish that are reputed to be a little bit more aggressive. Ryukins and bubbly-eyes are two examples of this. If you truly enjoy the way they appear, though, you shouldn’t be too put off since most of the time they’re going to be just fine.

Add Additional Calm Tank Companions

Finally, it’s a fantastic idea to have additional calm tank mates in your tank. Your goldfish will be less likely to become aggressive as a result of this.

If you’re unsure of what tank mates to acquire, pink barbs, white cloud minnows, and zebra danios are all excellent options (Find out about 7 more great danios). Try adding extra shrimp and snails if you don’t want any more fish.

What Should You Do When You Notice Aggression In Your Tank?


Can A Goldfish Bite?

This is what? There is no need to worry, though. Goldfish cannot bite humans and their teeth are not razor-sharp. They’re used to crush and grind food and are really rather flat, like human molars.

Can I Touch My Goldfish?

Yes, touching goldfish is OK. The rumor that touching a goldfish would cause it to die is just untrue. Your goldfish won’t die right away as long as you wash your hands first and handle them gently.

Do Goldfish Recognize Their Owners?

Goldfish have demonstrated their capacity for learning and information processing. Goldfish kept as pets may recognize different people and frequently the person who feeds them on a regular basis.

Final Thoughts

Are Goldfish Aggressive? You are now fully informed with goldfish aggressiveness. Even though violence is uncommon, it almost always indicates a problem, such as an overcrowded tank or a lack of food for your goldfish.

Additionally, there are several things you can do to prevent aggressiveness from happening, like making sure the tank is large enough, including lots of hiding spots, and including calm fish in the tank.

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