The Siamese fighting fish (Betta splendens), commonly known as the betta, or plakat (Thai: ปลากัด; lit: "fighting fish"), is a popular fish in the aquarium trade. Bettas are a member of the gourami family and are known to be highly territorial. Males in particular are prone to high levels of aggression and will attack each other if housed in the same tank. If there is no means of escape, this will usually result in the death of one or both of the fish. Female bettas can also become territorial towards each other if they are housed in too small an aquarium. It is typically not recommended to keep male and female bettas together, except temporarily for breeding purposes which should always be undertaken with caution.
B. splendens usually grows to a length of about 6.5 cm (2.6 in). Although aquarium specimens are widely known for their brilliant colours and large, flowing fins, the natural coloration of B. splendens is generally dull green, brown and grey, and the fins of wild specimens are short. In the wild, they exhibit strong colours only when agitated. In captivity, they have been selectively bred to display a vibrant array of colours and tail types.[unreliable source?]