The Siamese fighting fish (Betta splendens), or more commonly known as the betta, is a popular aquarium fish native to the Mekong basin of Laos, Cambodia, Vietnam, and Thailand. 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.
Siamese fighting fish usually grow to a length of about 6.5cm. Although aquarium specimens are widely known for their brilliant colors and large, flowing fins, the natural coloration of Siamese fighting fish are 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.
Siamese fighting fish feed on zooplankton and sometimes the larvae of mosquitos. In captivity, they can be fed a varied diet of pellets or frozen foods such as brine shrimp, bloodworms, daphnia and many others.
In the wild, betta spar for only a few minutes before one fish backs off. Bred specifically for heightened aggression, domesticated betta matches can go on for much longer, with winners determined by a willingness to continue fighting. Once a fish retreats, the match is over.
Siamese fighting fish prefer a water temperature of around 75–82 °F (24–28 °C) but have been seen to survive temporarily at the extremes of 56 °F (13 °C) or 95 °F (35 °C). When kept in colder climates, aquarium heaters are recommended.
Bettas are also affected by the pH levels of the water. Ideal levels for Bettas would be at a neutral pH (7.0) However, Bettas are slightly tolerant towards the pH levels. They have an organ known as the labyrinth organ which allows them to breathe air at the water’s surface. This organ was thought to allow the fish to be kept in unmaintained aquaria, but this is a misconception, as poor water quality makes all tropical fish, including fighting fish, more susceptible to diseases such as fin rot.
Bettas are found in many different colors due to different layers of pigmentation in their skin. The layers (from furthest within to the outer layer) consists of red, yellow, black, iridescent (blue and green), and metallic (not a color of its own, but reacts with the other colors to change how they are perceived). Any combination of these layers can be present, leading to a wide variety of colors.
In 1892, this species was imported to France by the French aquarium fish importer Pierre Carbonnier in Paris, and in 1896, the German aquarium fish importer Paul Matte in Berlin imported the first specimens to Germany from Moscow.