[4] The rainfordia is found in the Indian Ocean off Western Australia from Kendrew Island in the Dampier Archipelago to Kimberley and in eastern Australia from the northern Great Barrier Reef and reefs in the Coral Sea, as far south as Moreton Bay in Queensland.

[2] It was thought to be endemic to Australia but in 2019 it was recorded in the Raja Ampat Islands of West Papua in Indonesia.

[5] The rainfordia occurs in inshore waters where it is found in caves and crevices in coral reefs and is generally solitary.

[4] The rainfordia was first described in 1923 by the Australian ichthyologist Allan Riverstone McCulloch (1885–1925) with the type locality given as the Middle Island, Edgecumbe Bay, Whitsunday Passage, Queensland.

McCulloch originally placed it as being related to the genus Grammistes but in its own monotypic family, the Rainfordidae,[7] but it is now placed within the tribe Liopropomini.