Fish species whose numbers have declined significantly or have reached critical levels in all or part of their range. Conservation measures and artificial propagation have succeeded in restoring their numbers.

The IUCN Red List of Threatened Species currently lists 2,362 rare and endangered fish species, of which 1,235 are vulnerable, 665 are endangered and 462 are critically endangered. A further 6 ray fish species are listed as critically endangered in the wild and 64 species are listed as extinct.

Habitat loss and pollution are important factors in the decline of fish species, but by far the biggest threat is overfishing.