Reef Fishes – Reef Life of the Andaman – Part 9
A visit to the island of Koh Tachai often provides a special treat for divers: a large and easily approached school of teira batfish. The underwater landscape here is characterized by large granite boulders which provide the type of shelter that the batfish love. Hanging in the current, sometimes on their side, the batfish are very easily approached. Batfish take their name from their elongated pair of pelvic fins. Other varieties in the area include the pinnate batfish, seen here at Koh Bon and the similar golden spadefish, seen here in a school at Koh Torinla in the Surin Islands. This batfish’s tall proportions mark it out to be a juvenile. Very young batfish can be 3 times as tall as they are long. This striking design belongs to a young emperor angelfish. In adolescence, angelfish undergo a dramatic metamorphosis. The adult’s masked face and striped body are nothing like the young. The entirely different appearance of the juveniles is thought to protect them from adults of the same species, which otherwise might attack them to protect their territory. The distinctive blue ring angelfish can be seen on many Andaman dive sites individually or in pairs. The Similan islands also host regal angelfish and blueface angelfish. This individual from Boulder City bears deep scars and trails fishing line from its mouth. Butterflyfish brighten up any reef and there are many species in the Indian Ocean. This is a pair of copperband butterflyfish at Anemone Reef. and these are Meyer’s butterflyfish in the Similans, often found mixed with black pyramid butterflyfish. The raccoon butterflyfish is one of the most distinctive species. They are often mixed with redtail butterflyfish, the most common member of the family in the area. Bannerfishes are common throughout the area and are characterized by a very long spine at the front of the dorsal fin. Schooling bannerfish can be seen in shoals close to the reef or hanging above it feeding on zooplankton. At first glance the moorish idol may be mistaken for a bannerfish. It bears similar form and coloration, but belongs to a totally different family. Nevertheless they show similar habits. Like the bannerfish they can be seen alone or in large schools. These sailfin tang are feeding on algae covering the boulders at Rocky Point. Powder blue tang are seen at most sites within the Similans. “Tang” are also known as “surgeonfish”, so named because of the razor sharp spines just in front of the tail which can be used during combat. The tail spines of unicornfishes are particularly prominent. The ringtailed unicornfish also bears the spike on its head that gave the genus it’s name. This common reef fish is appropriately named the “crescent-tail bigeye”. Bigeyes typically inhabit dark spaces such as caves, where the large eyes help them see in low light. They occasionally form small aggregations like this one at Rocky Point. In open water their skin color adapts to the bright conditions by becoming paler, thereby making it less conspicuous. The juvenile emperor red snapper is one of the most distinctive of all reef fishes, but rarely seen. Named after the sea itself, the boldly spotted Andaman sweetlips has a striking design, but perhaps the most photogenic of all our reef fishes is the oriental sweetlips. Although often found alone, this species is at its most striking in numbers. Schools can be encountered among the enormous granite boulders at Christmas Point and Elephant Head Rock in the Similan Islands. The Andaman Sea is home to a large variety of groupers.