The Krabi mouth-brooding betta, Betta simplex, is a species of gourami endemic to Krabi Province, Thailand. It inhabits karst springs and wetlands, where it lives in areas close to the banks amongst vegetation. This species can reach a length of 8 cm (3.1 in). This species can also be found in the aquarium trade, and is considered to be seriously threatened due to the degradation of its restricted area of occurrence due to pollution and development of land for farming.