Small fish 3-8 cm long (rarely up to 20 cm), weighing up to 5 g. The body is naked or covered with bony plates. In front of the dorsal fin several free barbs. Marine, brackish-water and freshwater fish. Live in the waters of Europe, North Africa, Northern and Central Asia, North America. In fish farms Gasterosteus aculeatus and Pungitius pungitius are weedy fish and cause significant damage by eating the food of young valuable fish, their eggs and juveniles.

A family of ray-finned fishes of the order Gasterosteiformes, with 5 genera and 8 to 18 species. All representatives have barbs in front of the dorsal fin, the pelvic fin is absent in many species or is represented by a single barb and one or two soft rays, the pelvic shield is formed by the fusion of pelvic bones, scales are absent. When attacked by a predator sticklebacks spread their sharp dorsal and abdominal spines, usually tightly attached to the body, and these needles are thrust into the jaws of the predator. In the same way they ruffle and in fights among themselves (which happens very often) and in general in a moment of danger.

The family includes marine, brackish-water and freshwater species. The sticklebacks are very voracious. In ponds where they penetrate, it is difficult to breed any other fish. When fishing with a rod, they easily swallow the bait, even an empty hook. They have no commercial importance.

Spawn in April-May, during spawning they acquire brighter coloration. Fecundity from 100 to 120 eggs. Spawning lasts more than a month, and in nine-needle even until the end of July. During spawning males build nests, usually the size of a fist: first digs a hole in the bottom (three-needle), gaining sand in his mouth and taking it to the side, then brings in his mouth blades of grass and scraps of algae. With mucus from the sides of the body glue all this into a dense lump. The fish makes a tunnel in it. The finished nest in three-needle stickleback buried in the mud and almost invisible, and nine-needle almost does not differ from the leaves of the water plant to which it is attached. The male invites the female to the nest, where she lays eggs. The eggs are yellow, in some species amber in color, about 1.6 mm in diameter, clumped together. In multi-needle sticklebacks, some males look and behave like females, but they do not hatch eggs, but milk, and their offspring are taken care of by "ordinary" males. Immediately after spawning, the male chases the female away, as she may eat her own offspring, and fertilizes the eggs. The males aerate the nest, ensuring water flow, and guard the offspring for 10-14 days.

The newly emerged larvae are similar to all stickleback species, about 4.5 mm long, and are characterized by pigmentation. For the first few days, the male diligently watches the young and does not let them swim far from the nest. From the beginning of spawning the esophagus of the male overgrows, preventing him from eating, but with the end of the protection of offspring, the male can eat again and eats several fry.