TROPICAL FISH

Crystal-clear tropical waters are home to a myriad of colourful fish species.

A lack of plankton gives these tropical seas their clear, blue appearance and enables coral reefs and sponges to thrive - gaining energy from the sun's rays.

Often, huge numbers of species are confined to relatively small areas - like coral reefs - where they have had to develop complex social interaction.

One of the strangest behaviours is that of the colourful clownfish. Unlike most fish, clownfish are not affected by the powerful stinging cells of the sea anemone, and have evolved a mutual relationship with them.

Both benefit, with the clownfish getting a safe place to live and the anemone gaining protection from the few fish that could eat it, and even being fed titbits by its potentially deadly lodgers.

Butterflyfish get their name from their random swimming pattern. Many butterflyfish feed on coral and their slender heads and powerful jaws are also ideal for picking out food items from around the intricate coral heads.

Despite being less than 10cms long Sergeant Major fish are among the oceans' most aggressive inhabitants. What they lack in stature they more than make up for in pugnacity.

They will defend their home from all comers, no matter what their size. There are even reports of divers getting nipped when they have swum too close to the fish's territory.

A long nose, thin head and scissor like teeth make the Yellow Tang perfectly adapted for grazing algae from rocks and between coral heads. The solid yellow colour is broken only by two white spines on the base of the tail that are used to defend itself and to battle rival fish.

One of the most spectacularly coloured tropical species is the Mandarin fish, also called the Oriental Dragonette. The bright colours are to let other fish know that their skin is poisonous.

Among the larger species found in tropical seas are members of the wrasse family including the Humphead Wrasse. These fish can reach 2 metres in length but, despite their size, they are gentle giants feeding on molluscs and small invertebrates.

The common names for many of the species found in tropical waters often reflect their spectacular appearance.

Among the more unusual names are surgeonfish, Picasso triggerfish, Yellow-bellied Damselfish, Foxface Rabbitfish, Longnose Batfish, Fairy Basslet, Grunt and Cowfish!