Reef Fish Colours, Camouflage and Mimicry

Parrot fish Photo: AIMS

Fish use colour and pattern to recognise mates and other species. Colour is also used for camouflage; predators find it difficult to see fish against the colourful coral and algae. Some fish can change colour instantly. They do this by using their muscles to expand and contract small pockets of pigment in their skin.

Some fish mimic other fish, either to protect themselves from being eaten - by pretending to be a dangerous fish, or to get a feed themselves. The false cleaner fish which is a blennie pretends to be a cleaning wrasse. Cleaning wrasse are small fish that clean parasites from bigger fish. The bigger fish don't eat them as repayment for this service. The false cleaner gets close to the big fish in its disguise then nips some flesh from its unsuspecting larger prey.

Juvenile fish often differ in colour and shape from adults of the same species, and males and females differ as well, which is very confusing for fish biologists!