Gasterosteus Linnaeus, 1758
In front of the dorsal fin 3 (rarely 4, exceptionally 2 or 5) spines. Body usually covered with bony scutes (sometimes absent). Caudal peduncle with a keel (sometimes weakly expressed). Branchiostegal membranes attached to the isthmus.
Species belonging to this genus build nests.
Species 2; in Clofnam area 1 (more than 40 species have been described, but are presently considered only as forms; the second recognized species is G. wheatlandi Putnam, 1867, from Newfoundland to Massachusetts).
Recent revision: Berg (1965).
Species of this genus in the program:
Gasterosteus aculeatus