Below we offer you some brief explanations about fish groups that can commonly be seen during dives in South-East Asia, along with their typical outlines to help you identify them more easily. Click on the fish outline (they are not to scale) to be directed to a website with a lot of pictures of the respective species.
Batfish: Highly exaggerated dorsal, anal and pelvic fins. Young fish occur singly or in small groups and stay near reefs. In Asia, the Pinnate and Teira Batfish are commonly sighted. The juveniles have very long fins that become proportionally shorter as it grows.
Did you know that some juveniles mimick deadleaves (Orbicular Batfish) or toxic polyclad flatworm (Teira Batfish) as camouflage?
Butterflyfish: Round and small and have concave foreheads. They often have snouts for feeding from crevices and corals. Butterfly fishes are renowed for their striking colours and graceful swimming patterns. Most are active during the day and stay within 20m depth. Many feed on corals and small invertebrates. They are often seen in pairs. Did you know that some butterflyfishes such as the Spot-Banded Butterfly are know to form permanent relationships? If one dies, they never find another mate.
Bannerfish: The bannerfish belongs to the butterflyfish family. They have unusually long dorsal fins and are usually not more than 20cm long. At places like Sipadan and Layang Layang, the schooling bannerfish form a beautiful picture against the blue water backdrop.
Angelfish: They have long dorsal fins and rounded foreheads. Most angelfish are found in boulders, caves and large crevices. Most stay within a certain territory and they are one of rare species that feed on sponges among other things like algae, zooantharians, tunicates, gorgonians, hydroids and seagrasses. During their growth from juvenile to adult, they take on the most dramatic transformation. Did you know that the blue-ringed and six-banded angelfish can make clicking and drumming noises?
Surgeonfish: Somewhat horse-shaped or sloping face with spines sticking out from each side of their tail base. Most surgeonfish are docile and travel in schools. They feed on algae and seaweed. When in close proximity with divers, such as fish feeding session, take care that they don’t come too close as their scalper-like spine on each side of their tail can inflict nasty wounds.
Jacks: (aka trevallies), usually silver or blueish in colour, seen in open water at reef’s edge. The most frequently sighted jacks are the big-eyed, golden, black and blue-finned trevally. The Giant Trevally is an awesome sight and can grow up to 1.7m and weigh up to 170 kg. Did you know that during mating season, the silver jack changes its sex and turn totally black in colour? The black and silver couple stays together for a period before mating.
Barracudas: Long cylindrical and silver with faint markings. Large mouths with visible teeth. Large barracuda tend to travel alone, but smaller species may gather in groups. Schooling barracudas can number to a thousand and are a spectacular sight!
Snappers: Long tapered bodies and heads that slope towards the mouth. Common commercial fish. Most snappers are brightly coloured and active predators of smaller fishes, crabs shrimps, gastropods, cephalopods and planktonic organisms.
Sweetlips: Look quite similar to snappers, their most distince feature is their lips which seem to be swollen. Can be striped or spotted. Often found hovering under coral tables or just above reefs.
Damselfish: Small, oval fish that dart in and out of crevices on the reef. Algae feeding damselfishes are very territorial of their food turf. Damselfishes make up one the most abundant groups of coral reef fishes. Most are small, and are not bigger than 15cm. It is believed that the drape coloured species feed on algae and their brightly colour counterparts feed on plankton.
Fairy Basslets: (aka Anthias). Tiny colourful fish that brighten up the reefs and often stay in large aggregations swimming in tandem against the current above corals. Did you know that they have a harem-type of social structure? There is only 1 male surrounded by not less than 10 females. When the male dies or is eaten, the leading female will change into a male within 2 weeks.
Parrotfish: Beak-like teethplates and rainbow colours, much like parrots. They swim with their pectorals fins, and often scrape algae off hard surfaces. Parrotfish undergo female to male sex change according to growth stage. The colours between the sexes can be very different. Many parrotfish sleep in a cocoon-like mucus envelope to mask their scent from predators?
Wrasses: Generally smaller than parrotfish, usually foraging through sand and the reefs. Wrasses make up the second largest group of reef fishes after the gobies. They are very active and are constantly foraging for small crabs, shrimps, worms, and other small bottom dwelling invertebrates.
Squirrelfish: Pronounced rear dorsal fin that sticks out like a squirrel and very large glassy eyes. Hidden in crevices and under ledges. Squirrelfishes are nocturnal and during the day, they are found hidden inside caves or under large crevices. They come out to hunt shortly after sunset. They feed primarily on night animals such as crustaceans and echinoderms.
Cardinalfish: Small and reddish, with short snouts and 2 separate dorsal fins. They are small reef dwelling fishes and crustaceans. Some species, form large shoals over entire coral formations.
Did you know that male cardinalfishes incubate fertilised egg mass in their mouth for days until hatching?
Blennies and Gobies: Long bodies and generally perched on their pectoral fins. Most blennies are less than 15cm long, and are bottom dwellers, feeding on small invertebrates, algae and bottom detritus. Several species such as the False Cleanerfish have large teeth of the lower jaw that is used mainly for defense.
Flounders: (aka Flatfish), are amazing bottom-dwelling creatures, masters of camouflage. They change colour to blend into the bottom colours. Both their eyes are on the same side and they move independently. Did you know that flounder larvae looks exactly like fish larvae? However, when they grow, their bodies become compressed and one of the eyes migrates to the other side.
Scorpionfish: Stocky and rough bodies, with spiny dorsal fins that carry venom. Still and pretends to be a piece of rock. Scorpionfishes varies from mottled brown colour (for those found in rocks) to bright red in colour, found in caves and deeper sections of the reef.
Lizardfish: Elongated bodies and large upturned mouths. Often perched motionless on corals and bottoms. Lizardfish look somewhat like a cross between a monitor lizard and a chameleon. They lay like a monitor lizard with their bellies on the coral, and pretend like they are part of the “furniture”.
Filefish: Oval or diamond shaped with rough textured skin. Elongated pointy dorsal fins. Filefish are the sweetie pies of the reefs. They move daintily with slow measured movements. When there isn’t any big fish action to watch, the filefish can provide amusement and enjoyment.
Triggerfish: Oval or diamond shaped bodies with elongated pointy dorsal fins similar to a gun’s trigger. Most triggerfish species are solitary in habit and use their strong teeth to crush hard-shelled prey such as crabs and molluscs. Most triggers are same and harmless such as the pretty Picasso Triggerfish. In Asia, the larger species such as the Titan, Yellowmargin and Blue-finned triggers should be treated with respect, particularly during their nesting period.
Pufferfish: Round bodies and can inflate their bodies when threatened or scared. They are strange creatures with bodies encased in a bony carapace and fins are relatively small. They are slow swimmers, but capable of short, rapid bursts. The spiky ones are called Porcupinefish. The non spiky puffer has no scales and have beady eyes. Many pufferfish are toxic.
Goatfish: Long cylindrical bodies with two widely seperated dorsal fins, and a pair of long chin-barbels that are used for detecting food in the sand. The barbels are also used by males to attract females during courtship. When they are not used, you can hardly see them as they are tucked tightly under their chin.
Eels: Snake like and often hiding in crevices and holes. Eels are shy creatures in the day, and at most, peek out of their crevice. However they transform to another creature as night falls. Eels have been found free swimming in the night, foraging for food such as small fishes.