How Do Betta Fish Mate?

How Do Betta Fish Mate?

Betta fish are called Siamese fighting fish! They are extremely aggressive to their own kind. It is not uncommon for a female to kill a male when a breeder tries putting them together. If they are so aggressive that they frequently kill the opposite gender, how do they mate?

In the wild, bettas have much more room than in aquariums, so less aggressive fish can easily escape more aggressive ones. In aquariums, breeding must be done very carefully, and the breeder should be prepared for serious losses. At the very least, the fish will end up in rough shape and will be vulnerable to infections.

In this article, we will discuss breeding in the wild, aggression, breeding tanks, conditioning the breeders, and mating.

In the Wild

Mating depends on the species of betta, of which there are about 70, but for this article, we will focus on bubble nesting bettas. Some other species are mouthbrooders and hold their eggs in their mouths until they hatch. The common pet store betta is a hybrid of three different bubble nesting bettas.

Bubble nesting bettas create a nest made of bubbles that float on the water. The nest often consists of several layers, normally between 2-4 bubbles thick. Male bettas create these nests before spawning, using a mix of saliva and water.

A female will refuse to spawn with him if she doesn’t find the bubble nest impressive enough. However, if the male makes an impressive and sturdy bubble nest (some popping every now and then is normal), the female will spawn with the male. While wild bettas are much less aggressive than domestic bettas, they will still fight during the spawning process if they get frustrated. If this happens, the female often leaves, unless she is the aggressor.

During spawning, they will both go under the bubble nest and “embrace”. During the embrace, the female will release eggs which the male will then fertilize. The purpose of getting so close to one another is to increase the rate at which eggs are fertilized, since external fertilization has poorer results than other fertilization methods.

After dropping some eggs, the female will freeze, stop moving, and drift to the ground. The male will gather up the eggs and place them in the bubble nest. After the female recovers, they will repeat the process until she is out of eggs. Finally, the female leaves the eggs with the male.


Domesticated bettas were bred specifically to fight. Similar to cock fighting with roosters, betta fish were pitted against each other, and the strongest and most aggressive would win (and live). This often resulted in the death of the weaker one, meaning only the most aggressive would live to pass on their genes.

Since wild bettas have the advantage of more space and less aggressive partners, they almost never die during breeding. They often sustain some small fin tears and the like, but nothing major.

Domesticated bettas kill one another during mating far more often than anyone would like. If you spawn two bettas, you essentially retire them from being show bettas, as they lose large portions of their fins and scales, if they survive.

Most of the time these fins and scales will grow back. However, they leave a “wavy” pattern in the fins, and the scales can grow back without any coloration, ruining the look of your betta.

The aggression of keeping bettas together is one of the worst aspects of bettas. Just imagine a school of bettas flitting about a tank. If you’re okay with a little less color, wild bettas can do just that.

Breeding Tank

The set-up of a separate breeding tank is essential for the survival of your bettas and the young. If you attempt to spawn the bettas in their own tank, the chances of them spawning are much lower than the chances of them fighting.

By introducing one of the bettas to the other’s tank, you are essentially just adding an intruder. In the wild, male bettas have a territory that is about three-square feet, and betta tanks are rarely over 10 gallons. Since their tanks are much smaller than their territory, they will attempt to kill any intruder.

By setting up a separate breeding tank and introducing both bettas there, neither will have an established territory, so they will have a chance at breeding. Breeding tanks should be at least ten gallons, though you should start by only filling them about halfway, no more than 6 inches.

Provide some hides and minor decor for the female betta to hide in and behind.

You must have several areas where the male will not be able to see the female and vice versa. You also need to include something that floats and will stay floating, whether it be some Indian almond leaves, part of a styrofoam cup, a decoration sticking out of the top of the water, or floating plants. I personally use floating plants, primarily red root floaters.

Most importantly, you cannot have any substrate in the tank. Even a nice sand substrate would prevent the parents from finding all the babies and bringing them up to the nest. Any babies left on the ground will die.

Conditioning the Breeders

Another way to ensure that you have a successful spawn is to condition your bettas. During the conditioning, the bettas must be kept in separate tanks. Raise the temperature by 2 degrees, but do not let it exceed 82 degrees.

You will also need to change the diet a bit. Adding in live food, mainly California blackworms will result in great success. Other live food includes fairy shrimp, baby brine shrimp, daphnia, tubifex worms, and various insect larvae.

Mosquito larvae and bloodworms are an example of such larvae that are great for conditioning bettas. In addition, you can get these for free by laying out a tarp with some water in your backyard. Soon, midge flies and mosquitoes should come along and lay their eggs, then you can collect the larvae.

Feed your betta 3-5 protein rich meals per day. This helps the female make and hold more eggs, resulting in more babies, as well as making her stronger. The male will be able to display stronger coloration, and he needs to be fattened up because he will not eat while taking care of the babies.

The conditioning period should continue for 2-4 weeks, as this will provide enough time for your bettas to build their fat reserves and muscle. After the conditioning period is done, you will be able to carefully put them together in order to spawn them. If the spawning fails, separate, recondition, and try again.


When domesticated bettas mate, it is essentially the same as the wild bettas. The male needs to have a bubble nest ready, and the female will approach him. He will display, and if she likes his display, she will follow him over to the bubble nest.

Once the bubble nest passes inspection, they will mate. They will wrap around one another, and the female will release eggs that the male fertilizes. As long as you don’t have any substrate in the tank, they will be able to find all the eggs and bring them to the nest.

One of the issues with domesticated bettas and breeding is that it is not uncommon for either the male or female to eat the eggs and/or the young. The female needs to be removed as soon as spawning is over, but the male should be left in the tank with the eggs.

Not only will the male start to become extremely aggressive towards the female, but it is more common for females to eat the eggs. In addition, leaving the female in the tank may stress the male out so badly that he eats the eggs.

In conclusion, betta fish mating in captivity is much more difficult than it is in the wild. They have to be carefully prepared then put together, rather than finding one another. While it is not impossible, the aggressive nature of the domesticated betta makes it difficult for them to mate.

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