Sargocentron violaceum
Sargocentron violaceum, the violet squirrelfish, is a nocturnal species of squirrelfish in the genus Sargocentron. It can be found in the Indian Ocean and the Pacific Ocean from Aldabra and the Laccadive Islands to the Society Islands, north to Ryukyu, Japan, south to the southern Great Barrier Reef, and from Palau to the eastern Caroline and Marshall Islands in Micronesia. It is an uncommon inhabitant atoll reef flats, lagoon patch reefs, and steep outer reef slopes. It is a solitary and secretive species and can occasionally be seen in small crevices in clear water habitats. It is usually among rich coral growth and it mainly feeds on benthic crabs and shrimps. References

violaceum
Fish of the Pacific Ocean
Taxa named by Pieter Bleeker
Fish of the Indian Ocean
Fish described in 1853