Definition of fatheads:
(n) :
(derogatory) An idiot; a fool.
(n) :
A labroid food fish of California; the California sheephead. Semicossyphus pulcher.
(n) :
A cyprinid fish of the Mississippi valley, Pimephales promelas, the black-headed minnow.
(n) :
A blobfish, Psychrolutes microporos
(n) :
Any of several species of fish of the genus Cubiceps