Betta splendens

The Siamese fighting fish (Betta splendens), also known as the betta, 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. This species is native to the Mekong basin of Thailand, Laos, Cambodia, and Vietnam and is mostly concentrated in the Chao Phraya river in Thailand. The fish can be found in standing waters of canals, rice paddies and floodplains. It is listed as Vulnerable by the IUCN. 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. Although popular as an aquarium fish, the IUCN has classified B. splendens in the vulnerable category. The fish is naturally endemic to Thailand and can be found in shallow areas in marshes or paddy fields. The primary threat is due to habitat destruction and pollution, as farmlands continue to be developed across central Thailand. Betta splendens feed on zooplankton, crustaceans, and the larvae of mosquitoes and other water-bound insects. In captivity they can be fed a varied diet of pellets or frozen foods such as brine shrimp, bloodworms, daphnia and many others. They are naturally insectivores and do not typically or naturally consume vegetation, however, they may consume the food of other tank mates if available, even vegetable matter. Male bettas will flare their gills, spread their fins and twist their bodies in a dance if interested in a female. If the female is also interested she will darken in colour and develop vertical lines known as breeding bars as a response. Males build bubble nests of various sizes and thicknesses at the surface of the water. Most tend to do this regularly even if there is no female present. Plants or rocks that break the surface often form a base for bubble nests. The act of spawning itself is called a 'nuptial embrace', for the male wraps his body around the female; around 10–40 eggs are released during each embrace, until the female is exhausted of eggs. The male, in his turn, releases milt into the water, and fertilization takes place externally. During and after spawning, the male uses his mouth to retrieve sinking eggs and deposit them in the bubble nest (during mating the female sometimes assists her partner, but more often she simply devours all the eggs she manages to catch). Once the female has released all of her eggs, she is chased away from the male's territory, as she will likely eat the eggs.If she is not removed from the tank then she will most likely be killed by the male.