[4] This species attains a maximum total length of 35 centimetres (14 in).

[2] Genicanthus spinus is found in the southwestern Pacific Ocean.

[1] Genicanthus spinus Is found on rock and coral reefs at depths between 30 and 60 metres (98 and 197 ft) (at least).

it is normally encountered in groups that swim high in the water column, these are harems of 1 male and as many as 4 females.

[2] Genicanthus spinus was first formally described in 1975 by the American ichthyologists John E. Randall (1924–2020) with the type locality given as Bounty Bay on Pitcairn Island.