Gasterosteus - Sticklebacks

Gasterosteus is a genus of ray-finned fishes belonging to the family Gasterosteidae, the sticklebacks. These fishes are found in freshwater, brackish water and marine habitats in the Holarctic region.

There are currently 5 recognized species in this genus:

Gasterosteus aculeatus Linnaeus, 1758 (Three-spined stickleback)
Gasterosteus islandicus Sauvage, 1874 (Iceland stickleback)
Gasterosteus microcephalus Girard, 1854 (Smallhead stickleback)
Gasterosteus nipponicus Higuchi, Sakai & A. Goto, 2014
Gasterosteus wheatlandi Putnam, 1867 (Black-spotted stickleback)