The Labyrinth fish are a group known for their ability to breath atmospheric oxygen in the event the water they live in becomes depleted of oxygen or polluted. The organ that allows them to do this is called the Labyrinth and is located in the head just behind the gills. The labyrinth looks like a maze which traps air in its' many folds. The oxygen from this air is then absorbed directly into the bloodstream from the labyrinth organ.
Most Anabantoid males build bubble nests during the breeding season.
The male also guards the eggs until they hatch. See Breeding Freshwater Fish for a more information. Perhaps the most famous of the Labyrinths is the Siamese Fighting fish, Betta splendens . Males of this species will not tolerate each other and will fight to the death although they are otherwise a good community fish.