How do Betta fish mate if they always fight with each other? — Sophie, Fort Myers, Fla.
Marshall Brain Answers:
Male Betta fish are aggressive. That’s why, at the pet store, you see male Betta fish in their own individual containers. A group of female Betta fish can share one aquarium, but males need to be alone. At least until it is time to mate.
Male Betta fish build bubble nests when they are ready to mate. You can see a bubble nest in this video (the bubbles are made of saliva):
To encourage this behavior, at the aquarium store you can buy little plastic tanks called breeder tanks that go inside a larger aquarium. You can put a mature female in a breeder tank in a male’s aquarium to encourage the male to make a bubble nest. Extra feeding of male and female also helps. Or you can put a female in with a male and provide lots of hiding places for the female (plants, rocks, etc.). Once the nest is done, you can put the female in with the male, who will squeeze her to release the eggs. This is potentially fatal to the female. The eggs float into the bubble nest. Once they are done mating, the female can be removed and the male will tend the eggs.
The male will keep the eggs clean and also has a chemical in his saliva that releases the baby fish from their eggs. Once the babies hatch the male can be removed. The baby fish will grow quickly, and soon the males all have to be put in separate containers when they start to fight.
This is one of those cases where it is probably easier to buy Betta fish at the pet store rather than trying to raise your own. But if you want to try it yourself, there are many pages on the Internet filled with tips.