Mr. Fish
Beta males, in most of the species anyway, (including our pet store favorite, B. splendens), are very aggressive, even more so during the breeding period. They'll likely chase and kill the female if she sticks around and even attack their own reflection in a mirror.
Betas belong to a group known as labyrinth fishes, which means that they can breathe atmospheric air. And you thought only whales and dolphins could do that! This came about as an adaptation to living in small, warm, organically polluted water. Because their natural habitat is oxygen-deficient, they evolved an accessory respiratory system, another breathing organ, known as the labyrinth. The Siamese fighting fish can thrive in a... ... little beta fish bowl, because he doesn't have to take oxygen from the water, as long as he can get to the surface.
Baby betta fish are also dependant on daddy, who builds thier nestout of little air bubbles from his mouth. So that's what those annoying, tiny bubbles are in all those beta bowls!
