Are Bettas Aggressive? (6 Signs Of Aggression)

Betta fish have a reputation for getting into fights in the tank, which is why they are also known by the nickname “Siamese fighting fish”. If you’re looking to get some bettas of your own, you will want to know if the rumors are true: are bettas aggressive?

In this article, you will find out everything you need to know about the temperament that you can expect from betta fish, including when and why they might feel inclined to compete with other fish and what you can do to avoid having a fight on your hands.

Are Betta Fish Aggressive to Other Fish?

Betta fish have an aggressive nature, and they can fight and even kill other fish in their tanks. In the wild, males often get physical with each other to claim and defend their territory. The natural habitats of betta fish are generally low in food resources, and they need to eat a lot of protein to survive, so they defend their access to these resources with their lives.

Another reason why betta fish fight is to impress females and increase their chances of breeding. Males build bubble nests at the surface of the water that they use to attract females and ultimately protect any eggs that are lain. Male bettas are likely to fight off any fish that they see as a threat to these nests to keep them looking impressive for potential mates.

One of the most desirable qualities of the betta fish is their beautiful coloring and magnificent fins, but this flamboyant appearance is actually closely related to their aggression. Like many other species, male betta fish attract females with their colorful appearance, and they will get into fights with other males, or other colorful fish, to assert their dominance and establish their position as the lead male.

Although aggression is much more common in male betta fish, females can also get physical with each other if they are in a group together. Female bettas will generally have a hierarchy within their “harem” that is dependent on who is the most dominant, and they will sometimes fight to establish their social standing.

Can Betta Fish Live with Other Fish?

In general, betta fish are most aggressive towards other betta fish, so you have to be very careful about how many you have in a single tank. Female betta fish are much less likely to fight one another, and a small group will normally become comfortable together in the same tank, but males are usually more difficult.

Male betta fish are known to attack one another just because they are in the same space, so it is not recommended to have two male betta fish in one tank. Male bettas can also act aggressively towards female bettas, and a lot of owners will always keep their male betta fish separate from any other bettas unless they are trying to breed them.

Male betta fish, however, don’t have to live a solitary life, and they can live peacefully alongside non-aggressive fish from other species. Male betta fish don’t usually have a problem living with other fish species unless they are naturally aggressive or have bright/flowing fins that make them seem too much like another betta. Snails, shrimps, and Cory catfish are often safe tank mates for a betta.

At the end of the day, every betta fish does have its own individual personality, and some are much more aggressive than others. Before putting other fish in with a betta or adding a betta fish to a tank you already have, you will want to determine how aggressive they might be and try to reduce the risk of a fight breaking out.

Betta Bule Mustard Butterfly Halfmoon  HM Male or Plakat Fighting Fish Splendens  on Black Background.

Signs Of Aggression in Betta Fish

If you are putting betta fish into a tank, you need to be ready to spot the signs that they are starting to feel aggressive. You might think that a fight is always going to be quite obvious to notice, but some of the signals that bettas give off are more subtle, and you aren’t going to have eyes on the tank at all times.

Gill Flaring

The first sign that your betta fish are becoming aggressive is when they try and make themselves look larger and more intimidating. If your bettas are flaring their gills, it is usually a signal that they are trying to intimidate other fish.

Spreading Their Fins

Along with flaring their gills, bettas will spread out their fins so that they appear to be bigger and stronger than a potential opponent. They are hoping to scare off the other fish and win the battle for dominance without having to get physical.


If the fight isn’t decided by their posturing and intimidation, then things will become physical and violent. One of the most common ways that bettas will try to hurt each other is by aggressively ramming their bodies together.

Fin Nipping

A particularly dangerous aggression tactic amongst betta fish is to nip at their opponent’s fins, trying to bite off chunks and cause harm. If these bites are bad enough, they can lead to fin rot and ultimately become fatal for the injured fish.


There are many major and minor injuries that betta fish will sustain through combat, and you might become aware of these before you actually witness any fights. If you notice chunks of fin missing, tears, dropped scales, or red marks on the bodies of your betta fish, they are probably fighting when you aren’t looking.

Changes in Behaviour

Another sign that bettas are getting aggressive with each other is sudden changes in their behavior. One might be acting more submissive and withdrawn, or another might be acting more intense and dominant.

What Triggers Betta Fish Aggression?

It is not fully understood, even in the scientific community, whether all betta fish are innately aggressive or if it is related to the environment in which they are raised. Betta fish have unfortunately been forced to fight competitively for a long time in Southeast Asia, and they are raised under conditions that make them more violent. This implies that poor treatment and isolation make bettas more aggressive.

Aggression is usually triggered when betta fish are fighting to defend their territory from other bettas. More often than not, a male betta fish will be triggered when they feel threatened by another competing male, but that is not the only time that it will occur. Stress from an unstable or unsuitable environment can also cause bettas to act aggressively.

Bettas can become physical and aggressive with other fish too, and it is generally believed that they do so because they either feel vulnerable or they feel the need to establish their own position. It is believed that brighter colors and large, flowing fins trigger aggression from bettas because these characteristics are used to show dominance within their own species.

It is also believed that betta fish can become more aggressive during feeding times, particularly if they are feeling exposed, as they try to defend their meal and their right to eat. If male bettas have built a bubble nest, they are also more likely to act aggressively to defend it and protect it from others.

Will A Betta Stop Being Aggressive?

Some betta fish are naturally much more aggressive than others, but there are very few that will always be aggressive all of the time. If you are aware of the specific triggers which are leading to your bettas becoming violent, it is possible that removing or reducing these can bring them back to a peaceful existence.

If your betta fish have just been introduced to a new tank, they may act a little more aggressively as they adjust – some people even report bettas attacking their own reflections in the glass. If the tank is safe, free from other aggressive fish, and meets all of their needs, they should calm down after a couple of weeks.

Once they have settled in, however, bettas that still act aggressively under certain conditions are doing so for a reason, and unless those conditions change then their behavior is likely to stay the same. Bettas will rarely stop being aggressive of their own accord, so you will need to make some adjustments if you want them to happen.

How To Make Betta Fish Less Aggressive

There are always things that you can do to help your betta fish feel more comfortable, less stressed, and ultimately less aggressive in their tank. The most important thing to consider is what may be triggering the aggressive behavior in the first place so that you can address it directly.

Keep Male Betta Fish Separate

Keeping your male betta fish away from other bettas is one of the most important ways to reduce aggression – most hobbyists won’t even keep males and females together unless they are actively breeding. Males should be visibly separated as well as physically removed because they can become aggressive even through a pane of glass.

Avoid Threatening Tank Mates

Some betta fish find it hard to live alongside any other animals at all, and even the more docile bettas can fight with the wrong tank mates. Brightly colored fish with flowing fins are often seen as a threat, and any fish species that are known to act aggressively should definitely be avoided.

Increase the Size of Your Aquarium

Having more room to move around can make a big difference for your bettas because they will be able to establish their own territory. It is still unlikely that two males will get along in the same tank, but they are more likely to be peaceful around other species in a larger tank.

Provide Additional Hiding Spaces

Another way to help your bettas to feel more secure and less threatened by their tank mates is to give them more places to hide. Vegetation and scenery can greatly reduce the amount of stress that your bettas are feeling and distract them from focusing on each other.

Ensure Stability

Betta fish need to be in a stable environment if you want to avoid stress and aggression. The levels of ammonia and nitrate in their water need to be carefully monitored, and the water itself should be kept at a consistent, safe pH level and temperature.

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Which Betta Fish Is the Most Aggressive?

Of all the different varieties of betta fish out there, Plakat Bettas are considered to be the most aggressive. They were actually bred in Southeast Asia specifically for the sole purpose of fighting and are even known to try and jump out of their aquariums.

Recap: Are Bettas Aggressive?

So, are betta fish aggressive? The answer is yes. They didn’t gain the name “Siamese fighting fish” for nothing. Bettas are well known for fighting amongst themselves and with other fish species, sometimes causing serious injuries and even death.

Female bettas can often live together in small groups, but male bettas usually need to be kept completely separate from other betta fish. If their conditions are stable and their needs are met, most betta fish can live alongside non-aggressive fish species but some have a tendency to fight anything in their tanks.