Brook Stickleback, Culaea inconstans

Specimen from museum collections by Shawn Crouse, NJ Bureau of Freshwater Fisheries








The body of the brook stickleback is without scales and is olive to green with lighter spots.  The average length of the brook stickleback is 2.5 inches. It has 4 - 6, usually 5, short dorsal spines, each having a sail-like membrane and curved backwards.The pelvic fins each have one spine and the anal spine is located directly beneath the last  dorsal spine.  The caudal peduncle is narrow and the caudal fin is rounded.



The brook stickleback only lives in freshwater where it prefers cool water and densely vegetated areas of lakes and rivers.  It eats a variety of small aquatic insects, crustaceans,  algae, and even the eggs and larvae of other fishes.  Spawning occurs from spring to early  summer (April - July).  The males, who turn black in colour, build a small round nest on the  stems of vegetation.  The male also provides parental care for its eggs and young, defending  against predators and aerating the eggs by fanning.