Green-Boned Butterfish

Odax pullus

The Green-boned Butterfish, also known as Odax pullus, is a ray-finned fish found predominantly around New Zealand, especially near the South Island. This species is easily recognizable by its color transformation throughout its life stages. Juveniles start with a golden-yellow hue, shifting to a dark green-blue as they mature. Adult fish generally exhibit a brown-yellow coloration, with males displaying a distinctive bright-blue color upon reaching maturity. These fish can grow up to 40 centimeters in length and weigh as much as 1.5 kilograms. Odax pullus inhabits shallow coastal waters, preferring rocky areas with abundant brown algae, particularly Carpophyllum. They are typically found at depths of up to 20 meters, with most occurrences shallower than 30 meters. As a primarily herbivorous species, their diet mainly consists of brown seaweeds, including Carpophyllum, Lessonia, and Macrocystis species. Divers encountering the Green-boned Butterfish can expect to see them in subtropical marine environments where they graze on algae. They are protogynous hermaphrodites, starting life as females with some transitioning to males as they grow. The species is considered of Least Concern according to the IUCN Red List, and it plays a minor role in local commercial fisheries.