Three-spined Stickleback

Three-spined Stickleback ©Jack Perks

Three-spined stickleback

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Scientific name: Gasterosteus aculaeatus
A diminutive but aggressive predator, the three-spined stickleback hunts tadpoles and small fish. It is also known for fiercely protecting its nest of eggs until they hatch. Look for it in ponds, lakes and rivers.

Top facts

Stats

Length: 4-7cm
Weight: 1g
Average Lifespan: 3-5 years

Conservation status

Common.

When to see

January to December

About

The three-spined stickleback is a small fish found in ponds, lakes, ditches and rivers. It is an aggressive predator, feeding on invertebrates and other small animals, including tadpoles and smaller fish. In the spring, the male develops a bright red throat and belly and performs a courtship dance to attract a mate. He builds a sheltered nest out of vegetation, under which the female will lay up to 400 eggs. The male then defends the nest from other fish until the young hatch up to four weeks later. The three-spined stickleback is the fish that is most likely to be caught when pond-dipping.

What to look for

The three-spined stickleback has a brownish back and silvery sides and belly. In spring, males develop a red throat and belly, and bright green flanks. Living up to its name, it can be identified by the three sharp spines on its back.

Where to find

Widespread.

Did you know?

Marine three-spined sticklebacks migrate out to sea in the winter, returning to freshwater rivers in the spring to spawn. Freshwater three-spined sticklebacks tend to be more sedentary, staying in the same place for their whole lives.

Male stickleback encouraging a female to lay eggs in his nest © Tom Hibbert