Callanthias australis was first formally described in 1899 by the Australian zoologist James Douglas Ogilby with its type locality given as off Norah Head north of Port Jackson, New South Wales.

[6] The shape of the caudal fin varies from emarginate to almost truncate with larger individuals developing long filaments from the tip of each lobe.

In Australia this species is found from Moreton Bay in Queensland south and west to Rottnest Island in Western Australia, it is also found off Norfolk Island in the Tasman Sea.

It is a diurnal species which shelters in caves and crevices at nights and flees to these as sanctuaries when disturbed.

[7] Spawning schools are formed between August and November when a small number of males will raise their dorsala nd anal fins and circle around 1 or 2 females before they all swim up the water column and release the sperm and eggs before descending.