Why Are My Angelfish Fighting?

Angelfish may fight for various reasons, including breeding when housed with other aggressive breeds, frequent water changes, lack of space, or lack of nutrients.

Although angelfish are considered mostly very peaceful fish, they will show aggression when they are not happy, as they are feisty, territorial, and very active fish in general. This is also a factor that could make it challenging to house angelfish with other fish types.

How To Determine Angelfish Fighting Versus Breeding

Due to angelfish being omnivores, meaning they will eat plants and animals, it pays off to have a clue about their potential behavioral issues.

An angelfish’s stipe patterns and colors help to keep them camouflaged, which helps them to creep up on their prey, as they are ambush predators.

This instinct will remain noticeable when they are kept as pets in aquariums, which is why it would be best to choose tankmates for them that cannot fit in their mouths or has natural defenses against them.

Before exploring all the other reasons why angelfish will fight, it would help to realize that fighting could occur as a sign of mating.

When angelfish fight, they will lock their lips. However, this is also the exact behavior you will observe when a breeding pair of angelfish forms in your tank.

It would help to take a moment to determine whether your angelfish are mating or fighting before thinking of a solution.

You can do this by determining the genders of your fish, and if one of the angels showing aggression is female, the chances are very high that you have a breeding pair on your hands!

You should note what happens after the angelfish has locked lips, as breeding angelfish will also chase each other before and after mating. You will know as they flick their fins to look bigger while nipping at each other.

Females will also exhibit this type of aggressive behavior when they are ready to lay their eggs. The breeding pair will eventually calm down and swim alongside each other for an extended period.

In the case where mating has occurred, it may be in your tank’s best interest to separate the breeding pairs, as they will be naturally more aggressive.

Three Angelfish in Heavily Planted Tank

Reasons Behind Angelfish Fighting

Because of angelfishs’ territorial natures, aggression is simply part of their characteristics. Angelfish will establish and communicate hierarchy among other angelfish in their tank through aggression, which means there isn’t always a set cause, but there could be reasons.

Let’s explore these reasons to give you some valuable insight:

Angelfish Get Aggressive When Housed With Aggressive Breeds

When other types of fish are in the tank with equal aggression as an angelfish, it will cause chaos in the sense of fighting and competition. This is why it would be best if an angelfish is the only dominant type of fish in a community tank.

It may also be good to do some research on what tankmates are compatible with angelfish to minimize the risks of any aggression and fights occurring.

Angelfish Get Aggressive Due To Too Frequent Water Changes

Changing the water in your tank too often will dramatically upset the social order amongst your fish.

This means that angelfish will have to re-establish their position in their tank after every water change to create a chemical signature.

When you change the tank water, it ultimately nullifies the pecking order, which means that new water could lead to fighting and power battles amongst angelfish and other fish in the tank.

Angelfish Become Aggressive Due To Insufficient Nutrients

When angelfish aren’t provided with enough food to eat, they will not only fight with other fish but may even end up eating them.

This means an angelfish will become highly aggressive, and more food with more nutritional value should be added to their diet immediately.

Angelfish Will Be Aggressive Due To Lack Of Tank Space

Because every angelfish has the potential to grow up to 10 inches, they will need enough room to swim in and take part in their everyday fish activities.

A tank size of fewer than 10 gallons would not be ideal for an angelfish, especially if more fish are in their tank.

The same is applicable for less than a 30-gallon tank with two angelfish. When angelfish become cramped in their tank, they will become aggressive and fight.

How Can You Keep Your Angelfish From Fighting?

You can do many things to prevent those heartbreaking fights between your angelfish and their tankmates. Let’s go over these things to put your mind at ease:

Isolate Aggressive Angelfish

It may help to isolate the aggressive angelfish if you only notice the behavior coming from one side. Placing the aggressive angelfish in a separate tank for a couple of days will help them to cool off, and they won’t get lonely over such a short period.

If anything, you can see this as a time-out to punish them for this behavior! Monitor their behavior when you place them back in their community tank.

Keep Your Angelfish Pairs Balanced

It would be best to keep the number of female and male angelfish in your tank as balanced as possible or in pairs.

If there are too many female angelfish in a tank, they will become highly aggressive when the time comes to lay their eggs. Additionally, too many males will also lead to fighting.

Keep Other Species Of Fish In A Community Tank

It may help if you have some smaller schooling fish in your tank that your angelfish can chase around. This will prevent your angelfish from bullying and chasing each other.

Less aggressive and larger fish or fish similar in size to angelfish that can defend themselves will also help to keep their aggression levels controlled.

Add Some Shelter In The Tank

Adding some decorations and plants in your tank would be best, enabling your angelfish to have their own territory or space to retreat to when they need it.

A large and open tank may also lead to fighting, as each angelfish has no choice but to let their instincts take over, resulting in fighting to defend their territory.


Seeing your beloved angelfish fighting could be discouraging, especially if you’re a relatively new fish keeper or not familiar with an angelfish temperament.

However, by knowing the signs and some solutions, you will soon get the hang of it and once again see your angelfish playing and living together in a calm and civilized manner!