Betta raja is a species of betta endemic to the island of Sumatra in Indonesia. It is an inhabitant of swamps in lowland forests.

With a body length of 6-7 cm (without fins) Betta raja belongs to the medium sized Betta species. They are peaceful, somewhat shy animals that are best kept in company with conspecifics and other calm and peaceful fish. They go down in rough company. Betta raja are undemanding in terms of water values, except for breeding. Then you should offer soft and slightly acidic water to the mouth breeders in the male sex. The care temperature should be 24-26°C, for breeding 2-3°C warmer.