The fighting fish, commonly known as Betta, is a freshwater ray-finned fish found in the Southeast Asia region. Betta is usually small in size, but they are energetic and colorful. Currently, there are around 75 species of Betta recorded worldwide, with Malaysia having approximately 28 species, with 10 of them being endemic.

The emerald-spot fighting fish or Betta livida, is one of the endangered fighting fishes, which is rare and endemic to the northern Selangor and southern Perak states in Peninsular Malaysia. It belongs to the family Osphronemidae and is locally known as ikan picat or laga sungai besar in Malay (Zakaria-Ismail et al., 2019). It inhabits peat swamp areas and blackwater streams, which are highly acidic and have a pH value of five or less. In general, this species occurs in well-shaded shallow and stagnant water, which is less than one meter (Zakaria-Ismail et al., 2019).

The species epithet is derived from the Latin word, lividus meaning jealousy, which refers to the green eyes of this fish species. The flanks of this species have an iridescent green blotch. Betta livida exhibits sexual dimorphism, whereby the males are more colorful and have longer dorsal fins than the females when they reach maturity. Also, the posterior rays of the male can reach beyond the base of the caudal fin and up to one-third of the caudal fin (Zakaria-Ismail et al., 2019). It can grow up to 36.3 mm in length. Its diets include insects and small invertebrates (Ng & Kottelat, 1992).