As the name suggests the fish has three dorsal fins and has an extremely variable colouration. Most commonly white/cream splotches on an olive background.

Common in the South Island of New Zealand, in rock pools and depths down to 30 metres, also in reef areas of broken rock with kelp.

Feeds on benthic invertebrates.

Females lay up to 4 batches of eggs between May and November. The nests are laid on smooth sloping rock faces and one male may keep guard on up to 9 nests at a time.

A Treasury of New Zealand Fishes: Graham