A feature of the whole group of Labyrinthfish is the extra breathing accessory - the labyrinth organ - which is located in the head just behind the gills. This organ consists of a mass of convoluted tissue into which moist air, gulped at the surface, is stored and from which oxygen can be extracted. This organ is of enormous benefit to the fish should the waters in which they live become depleted of oxygen through pollution. The group, whose members have their natural habitats in the Southeast Asia, contains fish of modest and giant size, of peaceful and predatory dispositions. The predatory genus, Ctenopoma, is found in equatorial Africa but, while some of these fish are quite beautifully marked, careful consideration has to be given as to the fish that they are kept with.
The popular and numerous species of gourami belong to the Belontidae family. These fish have adapted pelvic fins that are mostly single filaments with taste buds at the end. Another family member is the Siamese fighting fish, Betta splendes. All specimens found in the aquatic dealers are captive bred; wild specimens do not have the bright colors or the elaborate finnage.
The gourami family is famous for making bubble nests. Usually the males a bubble nest by blowing little soapy bubbles filled with saliva and air. The bubbles float on the surface of the water underneath plants. It is the males who brings the female eggs into the nest and protects them until they are ready to hatch.
The kissing gourami, Helostoma temmincki, belongs to the Helostomidae family and the very large giant gourami, Osphronemus goramy, is the sole species in the Osphronemidae family. These fish can be kept as part of a community collection, as solitary specimens, or in a single-species collection. The majority are bubble-nest builders - the males construct a floating nest of bubbles and saliva, under which the female is coaxed and the eggs expelled and fertilized. Males become very territorial when guarding the eggs and it is best to remove the female after spawning to save her from attacks by the male. An exception to this reproduction method is the chocolate gourami, Sphaerichthys osphromenoides, which is a mouthbrooder.