The McCulloch’s scalyfin is endemic to Western Australia occurring from the Recherche Archipelago to the Abrolhos Islands, and is the most abundant damselfish in the southern waters of the state. They have deep rounded and compressed bodies, and a rounded head with eyes close to a small mouth. Growing to a maximum length of 28 centimetres, the McCulloch’s scalyfin are Australia’s largest damselfish. Colour varies dramatically between adult and juvenile stages, but not between sexes, except during display and spawning. Adults tend to have a dark mottled appearance to nearly black with a blue trim around the edges of the fins, males may have pale yellowish white areas over the head and body. Juveniles have a bright yellow body, with an electric blue back with fine horizontal blue lines over the head and dorsal surface and small blue spots scattered over the yellow body. There is a blue-edged black ocellus or ‘false eye’ near the rear of the dorsal fin.
The McCulloch’s scalyfin occurs in high densities on shallow rocky coastal reefs to depths of 35 metres, where they are territorial and males can become highly aggressive when guarding eggs. They tend to live close to the substrate, finding crevices in which to create a nest. They have a varied diet, ranging from small invertebrates to plankton to algae.
Other common names include: Common scalyfin.
Occurrence at the Busselton Jetty
The McCulloch’s scalyfin is very common in the waters surrounding the Busselton Jetty. Brightly coloured juveniles no larger than a fingernail to large mature drab-looking individuals can be observed throughout the year, feeding upon the invertebrate covered jetty piles. They are continuously observed to be chasing fish, often larger than themselves, such as wrasse species and other scalyfins.
Image by: S. Teede