The Betta mahachaiensis, is a species of bubble-nesting fighting fish native to Thailand, where they occur naturally near the Gulf of Thailand. They inhabit stagnant waters in swamps, pools, and ponds. They can be found in brackish waters, with salinity levels between 1.1 and 10.6 parts per thousand. Betta mahachaiensis is capable of living in both freshwater and brackish water. This is unique among Betta fish. This species grows to a length of 5 - 6 cm. It is found in the aquarium trade.