Ninespine stickleback Ninespine stickleback The ninespine stickleback ("Pungitius pungitius"), also called the ten-spined stickleback, is a freshwater species of fish in the family Gasterosteidae that inhabits temperate waters. It is widely but locally distributed throughout Eurasia and North America. Despite its name, the number of spines can vary from 8 to 12. The body of the ninespine stickleback tapers to a very narrow caudal peduncle and the caudal fin is fan-shaped. The body is less deep and more elongated than that of the three-spined stickleback with a thinner and longer caudal peduncle, but the best way of distinguishing these two species is
Copella (genus) observation. The pectoral fins are positioned immediately behind the operculum or gill cover, while the pelvic fins are further back along the body, about midway between the head and the caudal peduncle. The dorsal fin is positioned above and slightly behind the pelvic fins, and midway between the pelvic fins and the tail fin is the anal fin. The tail fin is forked in shape. Males usually possess more elongated and ornate unpaired fins than females. In the case of "C. arnoldi", the tail fin of the male is somewhat asymmetrical, the upper lobe being larger than the lower lobe,