Source : Webster's Revised Unabridged Dictionary (1913)

Redmouth \Red"mouth`\ (-mouth`), n. (Zo["o]l.)
   Any one of several species of marine food fishes of the genus
   {Diabasis}, or {H[ae]mulon}, of the Southern United States,
   having the inside of the mouth bright red. Called also
   {flannelmouth}, and {grunt}.