information on the biology of species and the ecology of habitats found around the coasts and seas of the British Isles

Trigger fish (Balistes capriscus)

Distribution data supplied by the Ocean Biogeographic Information System (OBIS). To interrogate UK data visit the NBN Atlas.
Only coastal and marine records shown



The trigger fish Balistes capriscus is commonly known as the grey trigger fish. It is brownish green to grey in colour and reaches a maximum length of 40cm. The mouth is small and 'beak like' with fleshy lips. Body form is laterally flattened to allow manoeuvring in shallow rocky areas or wrecks that they inhabit. The first dorsal fin can be locked upright and then unlocked by depressing the second spine, the 'trigger'.

Recorded distribution in Britain and Ireland

Adult specimens have been recorded in increasing numbers around the western coasts of Britain and Ireland. There is no current evidence of a breeding population in Britain and Ireland.

Global distribution



Mainly rocky bottoms and floating wreckage at depths between 10-100 m.

Depth range


Identifying features

  • Brownish green to grey in colour.
  • Up to 40 cm in length.
  • Small, beak-like mouth with fleshy lips.
  • Latitudinally flattened body.
  • First dorsal fin may be locked upright or flat.
  • Not currently in British waters.

Additional information

Common in the Mediterranean, where spawning occurs in water temperatures above 12°C. As they are poor swimmers, it is likely they arrive in the Eastern Atlantic to the North coast of Angola via the Gulf Stream. They may increase in numbers in Britain and Ireland because of warmer seas due to global warming.

Listed by

- none -

Further information sources

Search on:


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

  2. 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.]

  3. JNCC (Joint Nature Conservation Committee), 1999. Marine Environment Resource Mapping And Information Database (MERMAID): Marine Nature Conservation Review Survey Database. [on-line]

  4. National Biodiversity Network (NBN) Atlas website. Available from:  Accessed 01 April 2017

  5. Picton, B.E. & Costello, M.J., 1998. BioMar biotope viewer: a guide to marine habitats, fauna and flora of Britain and Ireland. [CD-ROM] Environmental Sciences Unit, Trinity College, Dublin.

  6. 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).


This review can be cited as:

Reeds, K.A. 2008. Balistes capriscus Trigger fish. In Tyler-Walters H. and Hiscock K. (eds) Marine Life Information Network: Biology and Sensitivity Key Information Reviews, [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 17-08-2018]. Available from:

Last Updated: 20/08/2008