The ninespine stickleback (Pungitius pungitius), also called the ten-spined stickleback, is a freshwater species of fish in the Gasterosteidae family that inhabits temperate waters. Widely but locally distributed throughout the UK and along the Atlantic coast of North America, it is also found in many northern and eastern European countries, in Greenland and in Turkey, and in the Far East. Despite its name, the number of spines can vary from 8 to 12.
It lives in streams, lakes, ponds and rivers and favors thick submerged vegetation, as its small spines do not offer much protection. Like the three spined stickleback, they have a series of scutes or bony plates along the lateral line but, in freshwater populations, these are frequently reduced in number with a gap between the anterior and posterior plates.
During the breeding season (April to July), the male builds a nest suspended on a piece of waterweed, about an inch or so above the substrate at the bottom. The female is attracted by the male and she lays eggs inside the nest, but then departs, leaving parental care to the male. The male guards these eggs and the young fry when they hatch. Then, when they have their spines, he drives them away to look after themselves.
The colouring when not breeding is olive green to light brown, with a pale silver belly. During the breeding season, the males develop a black area around the pelvis and the pelvic spines become white. The eyes are dark with a gold ring around the pupils. The body is more elongated than that of the three spined stickleback with a thinner and longer caudal peduncle.