Three-spined stickleback (Gasterosteus aculeatus aculeatus)

Distribution data supplied by the Ocean Biodiversity Information System (OBIS). To interrogate UK data visit the NBN Atlas.Map Help



A small torpedo-shaped fish with a slender tail and broad fan-like tail fin, usually 5-7 cm long but occasionally up to 10 cm in length. Two to four, usually three, sharp spines are born on its back in front of the dorsal fin. The first two spines are long and strong while the third is small. The pelvic fin is reduced to a single fin-ray and one sharp spine. The dorsal fin is longer than the anal fin. The sides bear a few bony plates, the number of plates increasing with increasing salinity. The body is greeny brown in colour, sometimes black dorsally and often bluish with silvery scales and belly in brackish waters.

Recorded distribution in Britain and Ireland

Common in estuaries and coastal lagoons around Britain and Ireland, and in fully marine conditions from the northern Irish Sea and North Sea northwards.

Global distribution

Recorded from Novaya Zemlya, Norway and Iceland south the Mediterranean, North Africa and into the Black Sea. Also from Greenland to Chesapeake in west Atlantic, and Japan to California via the Bering Sea in the Pacific.


Found in shallow waters amongst seaweeds, seagrasses and pondweeds in freshwater, estuaries, rock pools and saline lagoons or coastal waters.

Depth range


Identifying features

  • Row of three sharp spines along the back.
  • Pelvic fin reduced to a single spine and one fin-ray.
  • Boney plates along the sides of the body.

Additional information

The three-spined stickleback breeds in early spring and summer. In the breeding season the males develop a bright orange to red colouration on the throat. The males build hollow nests from seaweeds and aquatic plants, into which they drive females to lay eggs that the males then guard until they hatch and the young leave the nest (see Wheeler, 1969; Dipper, 2001).

Listed by


  1. Dipper, F., 2001. British sea fishes (2nd edn). Teddington: Underwater World Publications Ltd.

  2. FishBase, 2000. FishBase. A global information system on fishes. [On-line], 2001-05-03

  3. Howson, C.M. & Picton, B.E., 1997. The species directory of the marine fauna and flora of the British Isles and surrounding seas. Belfast: Ulster Museum. [Ulster Museum publication, no. 276.]

  4. Muus, B.J. & Dahlstrom, P., 1974. Collins guide to the sea fishes of Britain and North-Western Europe. Wm Collins Sons & Co. Ltd: London.

  5. Wheeler, A., 1969. The fishes of the British Isles and north-west Europe. London: Macmillan.

  6. Wheeler, A., 1994. Field Key to the Shore Fishes of the British Isles. Shrewsbury: Field Studies Council.

  7. Whitehead, P.J.P., Bauchot, M.-L., Hureau, J.-C., Nielson, J. & Tortonese, E. 1986. Fishes of the North-eastern Atlantic and the Mediterranean. Vol. I, II & III. Paris: United Nations Educational, Scientific and Cultural Organisation (UNESCO).


  1. NBN (National Biodiversity Network) Atlas. Available from:

  2. OBIS (Ocean Biodiversity Information System),  2024. Global map of species distribution using gridded data. Available from: Ocean Biogeographic Information System. Accessed: 2024-05-21


This review can be cited as:

Tyler-Walters, H., 2003. Gasterosteus aculeatus aculeatus Three-spined stickleback. In Tyler-Walters H. and Hiscock K. Marine Life Information Network: Biology and Sensitivity Key Information Reviews, [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 21-05-2024]. Available from:

Last Updated: 04/02/2003