Betta is a large genus of small, often colorful, freshwater ray-finned fishes, known as "bettas", in the gourami family ('Osphronemidae').The best known Betta species is 'B. splendens', commonly known as the Siamese fighting fish.

All the Betta species are small fishes, but they vary considerably in size, ranging from under 2.5 cm (1 in) total length in 'B. chanoides' to 14 cm (5.5 in) in the Akar betta ('B. akarensis').

Wild Betta fish are hardy and eat almost any animal small enough for these small fish to consume, including worms, larvae of mosquitoes or other insects, and smaller fish. Their natural environment is often resource-limited, so many Betta species are generalist feeders.

While many Betta species are common and 'B. splendens' is ubiquitous in the aquarium trade, other bettas are threatened. The IUCN (International Union for Conservation of Nature) Red List classifies several Betta species as Vulnerable. In addition, 'B. livida' is endangered, and 'B. miniopinna' , 'B. persephone', and 'B. spilotogena' are Critically Endangered.

More Info: en.m.wikipedia.org