If you've ever put a male betta fish, also known as a Siamese fighting fish, near the tank of another of its kind (or even worse, in the same tank), then you know that these aggressive beauties love the thrill of the fight. What you might not know, though, is that these fierce foes actually display some rather sportsmanlike behavior when they fight.
Bettas are native to the rice paddies of Thailand, Cambodia, Vietnam, and Malaysia, where water is relatively low in oxygen. As a result, the fish adapted, evolving an organ that allows them to breathe when they break the surface of the water. Unfortunately, this also means they have smaller gills than most fish, so when they engage in high energy activities, they must periodically take a break and hit the surface.
While you might think this breather would provide a particularly aggressive fish a perfect opportunity to strike at his opponent while his defenses are down, the fish actually come up for air at the same time. The behavior is purely tactical, according to researcher Dr. Steven Portugal of London's Royal Veterinary College. "If your foe needs to breathe first, you might be forgiven for thinking this is the best time to strike," he says. "However, if your attack at this point is not successful, your opponent comes back to carry on fighting you with plenty of oxygen. Therefore, by both surface-breathing at the same time, neither of you are risking being attacked by the other during the ascent and descent from the surface."