Lunged Stickleback

A swift, fierce fish with spiny fins whose spiny mouth can pierce the current when it swims at full speed. Its capabilities have earned it the nicknames "The Cutter" and "Hard-To-Get."
Unlike others of its kind, the lunged stickleback can live in dried, muddy pools for a long time. Other than its gills, it can also breathe through its vestigial scales, which is a feature much more similar to that of amphibians. As such, apart from dealing with uninvited anglers, it also has to deal with an academic vote of no confidence in it still being a stickleback.