A fish called wonder

Deborah Smith Science Editor | March 3, 2009

A MASTER of disguise has been uncovered living in Australian waters.

The blue-striped fangblenny is the first fish found to be able to change its colour at will to mimic a variety of other fish.

Its repertoire of colour changes includes olive, orange, and black and electric blue, and it appears to use colour vision to achieve its incognito exploits, new research shows.

University of Queensland biologist, Karen Cheney, said that her examination of the little fish's eyes showed they should be able to detect different hues. They also have a habit of curling their tail around to touch their head, so they can see their body. "It is possible that fangblennies can view some of their own colouration," Dr Cheney said.

The only other creature known to be able to imitate other species is the mimic octopus, which alters its colour and shape to resemble lionfish, flatfish and sea snakes.

Dr Cheney and her colleagues had studied the habits of fangblennies on coral reefs in Australia and Indonesia. Their results are published in the journal Proceedings Of The Royal Society.

For food, fangblennies dart out and attack larger reef fish, nipping off tiny pieces of their fins, scales or mucus.

In olive mode they tend to hang out in shoals of similarly coloured damselfish, and in orange mode they mingle with yellow anthias.

"Their repertoire of disguises appears to prevent, or reduce detection by potential victims," Dr Cheney said. "They may also escape from predators by hiding in a large shoal."

Their most striking talent is to impersonate black-and-blue juvenile cleaner wrasse - fish that provide a cleaning service for other reef fish by picking parasites off their backs.

The researchers were surprised the fangblennies did not attack reef fish that came to have their parasites removed.

Dr Cheney said this probably helped maintain good relations with cleaner wrasse.

"Otherwise the cleaner fish could get aggressive and chase them away."

She has found that when the fangblennies are removed from a shoal they can revert to what appears to be their default colour, brown, within a few minutes. Brown ones tended to hide away in holes in the reef, Dr Cheney said.

http://www.brisbanetimes.com.au/news/national/a-fish-called-wonder/2009/03/02/1235842367776.html