Twister (fish)

Taxobox | name = Twister
regnum = Animalia
phylum = Chordata
classis = Actinopterygii
ordo = Perciformes
familia = Tripterygiidae
genus = "Bellapiscis"
species = "B. medius"
binomial = "Bellapiscis medius"
binomial_authority = (Günther, 1861)

The twister, "Bellapiscis medius", is a triplefin fish of the family Tripterygiidae, commonly found around the coast of New Zealand in rock pools and down to depths of about 2 m in reef areas of broken rock. It length is between 5 to 10 cm. It has a more rounded, blunter head than other triplefins.

Its non-breeding colouration is a mottled red-brown, often with a greenish tinge and there are about 6 darker saddles on the back and a dark band along the flanks. During the breeding season between May and August the male's breeding colours are striking: the body becomes blue-black and the pectoral fins turn a bright orange-red with green tips. Additionally, the first dorsal fin has blue and orange stripes running through it.

Nests are usually on vertical surfaces in the surge zone just below low water. Juveniles settle out of the plankton into tide pools from August to December when they are 15 to 20 millimetres long, but they live for only about 2 years.

The twister is non-aggressive and does not defend a territory, moving at random between rock pools. Their food consists of tiny crustaceans, amphipods and isopods, worms, and molluscs, and they have been observed biting off barnacle cirri.

References

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* Tony Ayling & Geoffrey Cox, "Collins Guide to the Sea Fishes of New Zealand", (William Collins Publishers Ltd, Auckland, New Zealand 1982) ISBN 0-00-216987-8