The Bigmouth Sleeper, Gobiomorus dormitor, is a member of the Sleeper or Eleotridae Family, and is known in Mexico as guavina bocona. Globally, there are four species in the genus Gobiomorus, of which two are found in Mexican waters, one in the freshwater drainage systems of the Atlantic and one in the freshwater drainage system of the Pacific Ocean. It has an elongate, cylindrical body and a large, broad head. The dorsal profile is gently arched to the dorsal fins and then slopes down to the caudal peduncle. The mouth is large and terminal with a projecting lower jaw, and this species has large lips and a pointed snout with a projecting lower jaw. All fins are spotted. The bigmouth sleeper is a brackish and freshwater species that inhabits creeks, canals, ponds and lakes. It can often be found inland, but also in coastal areas of fresh and brackish water.