Definition of sunfisher:
(n) :
Any of various large marine fishes of the family Molidae that have an oval compressed body.
(n) :
Any of various small freshwater fishes of the family Centrarchidae, often with iridescent colours and having a laterally compressed body.
(v) :
(intransitive) Of an animal such as a bull or a horse: to twist the body into a crescent shape and roll back and forth.