Tonguefishes and tonguesoles are the common names for the members of the Cynoglossidae family. The family members have both eyes on the left side of their head and margin of preoperculum completely covered by skin and scales. There is no spine in their fins and their dorsal fin extends far forward on head. Their dorsal and anal fins are attached to caudal fins and a rostral hook usually present below their mouth.
Members of the Cynoglossidae are found in the tropical and subtropical waters worldwide. There are 3 genera and 143 species worldwide. They commonly inhabit marine waters on mud and sand bottoms from 1 m to 1500 m depth. Some species occur in brackish waters near river mouth but they are rarely found in freshwater. They feed mostly on small crustaceans and other bottom-living animals.