sunfish

Short definition from Wiktionary

Noun

1. 1
   Any of various small freshwater fishes of the family Centrarchidae, often with iridescent colours and having a laterally compressed body.
2. 2
   Any of various large marine fishes of the family Molidae that have an oval compressed body.

Verb

1. 1
   Of an animal such as a bull or a horse: to twist the body into a crescent shape and roll back and forth.