any of a family (Gasterosteidae) of small scaleless bony fishes having two or more free spines in front of the dorsal fin and including marine, anadromous, and freshwater forms
sticklebacks
noun(stick-le-back)
a stickleback (Gasterosteus aculeatus) chiefly of fresh and brackish waters that typically has three dorsal spines —called also three-spine stickleback