Length up to 11 cm.
Weight up to 20 g.
Also called Prickleback, and sometimes referred to as a ‘tiddler’, this is a small fish, which has 2 to 4 dorsal spines (usually 3 spines), just in front of the dorsal fin. Larger fish are discouraged from swallowing Sticklebacks because of those dorsal spines which can be sharp and locked erect.
A favourite quarry of children with fishing nets in small pools, they hover and dart about in open water and are usually quite easily spotted and caught. It has a torpedo-shaped body which narrows towards the tail, which is either mottled brown or greenish, being silvery underneath. During the breeding season the male has a red underbelly and a bluish dorsal sheen. Similar to the Ten-spined Stickleback (Pungitius pungitius).
The male attracts the female to courtship with his bright red underbelly and by doing a courtship dance. He will build a nest with vegetation in which the female will lay up to 400 eggs. He will then defend the nest from predation, and will fan the eggs to ensure a plentiful supply of oxygen. After the eggs have hatched 4 weeks later he will protect the small fry and teach them how to defend themselves against predation. With a lifespan of up to 5 years, it is a fierce carnivore which feeds mainly on invertebrates, but it will also eat tadpoles.
Seen all year round in brackish water, freshwater or salt water environments, including rivers, streams, ponds, lakes and ditches, and in coastal habitats like estuaries and harbours. Native to Britain, a common and widespread species throughout.