Betta Fish Fight

How to Make Betta Fish Fight

Let’s preface this article by letting you know that forcing bettas to fight, or inciting aggression in any way, is animal abuse and punishable by law. Betta fish are intelligent animals capable of feeling pain and at least two emotions, possibly many more. Making them fight is not a difficult concept but making them fight and having both fish survive is.

Putting two male betta fish together in the same tank is normally enough to make them fight. Putting two female betta fish together in the same tank will also result in a nasty fight. Betta fish do not get used to one another’s presence and will continue to fight one another until they are either unable to fight or the other one is utterly dead.

In this article, we will cover putting bettas together, how to measure aggression, dealing with the aftermath, two females, two males, and successfully keeping bettas together.

Put Them Together

Bam. Simple as that. Put two betta fish together, and they will fight. Gender doesn’t matter to these guys either. Even if you put a male and a female together, they will fight, normally to death.

It is possible to house betta fish together, but this normally only applies to wild betta fish species, which have not been bred for aggression. However, with a large enough tank (at least three feet long, one foot high, and one foot wide), several female bettas can be housed together. Larger tanks are needed to house males together.

Now, why do betta fish even fight? The main reason is that they do not have enough space. In the wild, male bettas occupy a territory of about three square feet. If you provide very clean water, six square feet of space, and extremely dense vegetation and decorations, then maybe, just maybe, you can keep two male bettas together.

Either way, there will be some fights. No tank with two bettas avoids fighting, but with wild bettas, the fights tend to be minor, with only a few missing scales, bent fins, and torn fins. With domesticated bettas, the fights result in open wounds and fins entirely missing.

Measure Aggression

If you plan on putting bettas together, you should first do preliminary tests to measure how aggressive they are. These tests are not a full measure of aggression and are not overly accurate, but they can give you an idea of how aggressive the bettas are.

The first test, and the most common test is the mirror test. Hold a mirror, it can be any size that is easily moveable, even a makeup mirror, and hold it up in front of your betta. While betta fish are intelligent, they do not pass the self-image test. This simply means they do not recognize the thing they see in the mirror as “self”, but rather as something “other”.

Your betta should stare at the image in the mirror, and you can normally tell when it is looking at the mirror. If the betta looks at the mirror then looks away, it is not very aggressive. On the other hand, if it stays staring at the mirror, it may have some minor aggression, moderate aggression, or none at all. Finally, if the betta flares at the mirror, even if it immediately runs away, it is moderately to severely aggressive.

Other tests can also be done, from sticking a straw in front of your betta and measuring its reaction (most will flare, mainly because they are confused, but the chill ones will not), to even trying out tank mates. Tank mates are a great measure of aggression, but things can go south very quickly, so be cautious.


If you, for some reason, put bettas together and they fought, you will have to deal with the aftermath. Any wound that is exposed to aquarium water has a high chance of becoming infected. Pathogens are constantly in that water, but the betta normally has a strong enough immune system to fight them off.

By allowing the fish to become damaged, you risk them dying, even if you separated them early on. In fact, you may even see a fungal infection, which is very rare, as they can only set in on dead and decaying flesh, like the type you would find in a wound.

The good news is that you are unlikely to have to deal with parasites, but you will probably have to work with bacterial infections at the very least. Have a strong antibacterial on hand, such as Kanaplex or Erythromycin, and have a fungal medication as a backup.

If the fish has only some minor tears to the fins, you often don’t have to do anything other than some extra water changes. The addition of an Indian Almond Leaf can also help, as they release tannins that have antibacterial and antifungal properties, so they can ward off infection, but not treat it.

If the betta has severely torn fins and missing scales, keep a close eye on the wounds. Watch for redness or grayness appearing. The red could be healing, so keep an eye on it, but the gray is almost always a bacterial infection, so go ahead and treat for that.

If the fish is lying on the bottom of the tank and breathing heavily, the chances of survival are not good. Make the fish as comfortable as possible and do a large water change to give them fresh water.

Two Females

Keeping two females together is not better than keeping two males together. They are just as ferocious and vicious as the males, and since they are not weighed down by long fins, they are also much faster.

Putting two females together, even in a very large tank, will result in a fight. They do not establish territories like the males do. Instead, they establish hierarchies.

Successfully keeping five or more female bettas together is possible, but it must be done very carefully. Keeping two female bettas together is not. The females establish a hierarchy based on aggression and strength, so the most aggressive will be at the top.

After a few days of fighting, they will settle into their new position in life. There are often some minor (or major) scraps that occur but taking a fish out to treat and place back in is difficult. You would have to remove all the bettas in the tank, redesign the whole tank, and then introduce them all back at once. They will fight again to reestablish the hierarchy.

With two female bettas, there is no hierarchy, only one aggressive betta and one dead one. There will always be weaker betta, and that one will lose the battle.

Two Males

Unlike the females, keeping more and more males together just decreases your chances of a successful tank. In a very large tank that can provide six square feet of space (horizontal space is preferred over vertical space) that is heavily decorated and has dither fish, you can normally keep two males together.

In anything smaller than, say, a 75- or 100-gallon tank, the chances of success with domesticated bettas are slim. Dither fish can increase the chances, but I have never seen a tank with two male bettas under 75 gallons last.

Since bettas are sight predators and male bettas are aggressive on sight, adding in distractions can help. Dither fish are fish added in to either draw attention and aggression away from other fish or to show shy fish that the area is safe.

For bettas, any normal tank mate can work as a dither fish, though mid to top level schooling fish are the most successful dithers. That being said, you will have to be very careful when introducing them and monitoring them for the first several months.

In conclusion, putting any two bettas together will result in a fight. You don’t need to do anything special at all for these guys to fight each other. Heck, even the females will. The real problem with putting bettas together is getting them to stay alive because these little predators have teeth for a reason.

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