Raja Betta

About

Found in the lowland swamp forests of Sumatra, Betta raja is one of nearly 70 recognised members of the genus and belongs to the closely-related B. pugnax complex. It was widely misidentified as Betta fusca before being formally described, and is still sometimes confused with similar-looking relatives. Coloration runs to earthy brown tones accented with iridescent green or blue spots, and mature males are especially distinctive thanks to remarkably long pelvic fins that can extend well past the base of the anal fin. The anal and lower caudal fins carry dark marginal banding that sharpens the overall look. Like all anabantoids, this species has a labyrinth organ that allows it to breathe air directly from the surface. A useful adaptation in the oxygen-poor waters it calls home. In the aquarium it is best kept away from boisterous or large tankmates, which tend to stress it out; small, calm cyprinids or loaches from similar habitats can work well. It can also be kept as a pair or small group, which brings out some genuinely interesting social behaviour. Breeding follows the typical osphronemid embrace, and the male is a paternal mouthbrooder who incubates eggs for up to two weeks before releasing free-swimming fry. A tight-fitting lid is important, as the labyrinth organ in young fish develops in contact with warm, humid air at the surface.