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Are Betta Fish Aggressive? Understanding Their Temperament

Although I thought that I could keep it under control, what I quickly realized is that keeping multiple male betta fish together did not work. Generally speaking, are betta fish aggressive?

Quick Answer

Betta fish, especially the males, can be very aggressive and territorial, particularly towards other males. Females may at times also be aggressive, although typically less than males. There are ways to ensure that there is minimal aggression between betta fish and with other fish.

Keep reading to find out everything there is to know about betta fish aggression, territoriality, what kind of triggers they have, and what you can do to maintain the peace.

Can Betta Fish be Aggressive and Why?

There are quite a few factors to be aware of when it comes to the aggressive and territorial nature of betta fish, and I’ll do my best to cover all of it right now.

Male Betta Fish

It is true that as far as aquarium fish go that you might keep at home, male betta fish are some of the most aggressive and territorial of all. Male betta fish are very territorial and usually always exhibit some kind of aggressive behavior towards other males when they are in close vicinity.

If you see male betta fish encounter each other, they will likely spread their fins, flare their gill covers, engage in confrontation, and even start fighting physically. 

male betta fish looking at his reflection in aquarium glass

Although we can’t be sure exactly why these betta fish are so aggressive, it would appear to have something to do with fighting not only over territory, but also over the right to mate.

As is the case in the animal kingdom, many animals, such as the betta fish, are willing to fight to the death to protect the territory which they view as their own. For this reason, keeping two male betta fish together in the same tank is not advised.

The chances are almost 100% that at one point or another, they’ll have some kind of confrontation, which could likely lead to the injury or death of one of the fish, if not both. 

I made the mistake of keeping two male betta fish together once when I first started keeping fish, and it was one of the biggest mistakes I’ve ever made.

You would think that male betta fish would not be aggressive towards the females, because females are required to reproduce. This is in part true. Males tend to be much less aggressive towards female betta fish than towards other males. 

As far as breeding is concerned, females are of course not seen as competition like other males are, and females generally aren’t viewed as big a threat to the male’s territory as well.

However, based on my own experience, males can still bully females and harass them, especially depending on the specific fish. Remember that different betta fish have different personalities, with some males being more aggressive than others.

Just keep in mind that if you have a male and a female together in the tank, and it’s mating season, if they’re doing something that looks like fighting, it’s probably actually something else!

Female Betta Fish

As mentioned above, female betta fish are usually much less aggressive than males. However, they can still be aggressive at times. Female betta fish may be aggressive towards other males, especially if they feel like they are being harassed. Some female betta fish may also be aggressive towards other females.

Generally speaking, however, if you do plan on keeping several betta fish together, keeping females with other females usually goes best. These are often referred to as sorority tanks.

Once again however, just like with male betta fish, exactly how aggressive females are also comes down to individual personalities. You might be able to put four female betta fish in the same tank and they’ll do just fine, whereas two others might fight with each other. It really comes down to the luck of the draw.

Betta Fish Aggression Towards Other Fish

Unfortunately, betta fish aren’t just aggressive towards each other, but may also be aggressive towards other fish species. This is why keeping betta fish together in a community tank along with other fish can be difficult.

First and foremost, betta fish are often aggressive towards other fish that resemble betta fish. If you have a fish that has really bright colors and long fins, and are of a similar size, then betta fish may mistake them for other betta fish, and thus cause aggression to occur.

Therefore, considering what types of fish and other tank mates you keep with your betta fish is very important. As we’ll discuss further below, there are certain tank mates that are ideal for betta fish, and others that are not.

Betta Fish Aggression Triggers

There are several triggers that may cause a betta fish to become aggressive, so let’s take a quick look at each of the biggest ones.

  • Male betta fish will usually always become aggressive when they come into contact with another male.
  • Some male betta fish may also be aggressive towards other females, and females may be aggressive towards males and females as well, especially if they are in close proximity.
  • If a betta fish feels like it doesn’t have enough space and its territory is being encroached on, it will likely become aggressive towards other betta fish and other fish species.
  • Therefore, if the aquarium is too small for the betta fish and its tank mates, and if there aren’t enough hiding spaces, this can trigger aggression and territoriality.
  • Betta fish, especially males, may also become aggressive when they see their own reflection, such as in a mirror.

How to Minimize Betta Fish Aggression in an Aquarium

Betta fish can of course be pretty aggressive, but this doesn’t mean that it is impossible to keep them together with other fish. If you follow the tips that I’m about to provide you with below, keeping a betta fish along with other fish, maybe even other betta fish, is possible.

Space Matters

Perhaps one of the most important factors to consider here is the size of the aquarium. A general rule of thumb is that every inch of fish requires a gallon of water. However, for a betta fish to be comfortable, it’s closer to two gallons of water for every inch of fish.

That said, if you are looking to avoid any instances of aggression or territoriality, you might want to double that number for any community tank. 

If you are keeping your betta fish along with other fish, make sure that your betta fish has at least 8 or 10 gallons of room. The more space it has, the less likely it is to become aggressive or territorial.

The Right Tank Setup

To ensure minimal aggression in your betta fish, the tank setup needs to be considered as well. More than anything else, this means providing your betta fish with a lot of hiding spaces.

You really want to recreate its natural environment, which means providing it with a lot of rocks, caves, driftwood, plants, and other decorations. You need to provide your bait with hiding spots and places where it can feel secure.

Dividing up the tank like this will make the betta fish feel like it has its own territory. At the very least, if there are plenty of hiding spaces, other fish can also duck for cover. If the other fish are out of sight, your betta fish won’t be as likely to be bothered by them.

The Right Tank Mates

Finally, exactly what tank mates you choose matters as well. Of course, male betta fish should not be kept with other males, and if you keep them with females, keep the two above tips in mind.

As for other types of fish that might be suitable to keep with betta fish, tetra fish and corydoras are two good options. Guppies make for good choices as well, as do a variety of shrimp, snails, and even frogs.


The bottom line here is that you really do need to be careful in terms of which fish you keep with your betta fish, because they can be very aggressive, particularly the males.

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