Three-spine Stickleback

Gasterosteus aculeatus

Being most amenable, the stickleback flourishes in freshwater, saltwater and in varying degrees of brackish water.  It especially favors places around eelgrass beds and pilings.  Armored with thin bony plates, instead of scales, the Stickleback is quite small, often being less than 4 inches long.  The Stickleback spawns mostly in freshwater, where a male builds a nest and guards the eggs.