ADAPTATIONS
Brook Sticklebacks have a slender body and an extremely narrow tail. They have five to six spines in front of their dorsal fin. These fish do not have scales but do have small plates by their lateral line pores. They grow to be about two inches long. Adults are a dark green to black and have light spots on the sides. Spawning males are usually completely black. Male and females have a large head with large eyes. They have a small mouth and swollen lips, with a lower jaw that protrudes beyond the upper jaw. Brook Sticklebacks lack red muscle which limits their ability to swim for long periods.
