Butterflyfish, with their wonderful display of colours and patterns, are a common sight on the reefs and dive sites around Koh Lanta.
Sometimes confused with angelfishes, the family Chaetodontidae has over 100 species of butterflyfish, including coralfish and bannerfish.
Often brightly coloured yellow, red or white, with black, orange, or red markings, butterflyfish have thin, colourful, disk-shaped bodies, a small mouth, protruding snout, and can range in size from 8 cm up to 20 cm for larger species such as the lined butterflyfish.
Many have an eye-like spot on their rear and dark bands across their eyes used to confuse their predators into which way they might flee. These defensive patterns are often likened to those of butterflies, hence the name.
The dorsal fin is an uninterrupted row of tough spines, with a tail fin that may be rounded or concave but never forked.
During the night, Butterflyfish hide in cracks and crevices exhibiting markedly different colours, camouflaging themselves into their surroundings.
Butterflyfish tend to stick to a particular home territory, constantly grazing on coral and rock formations in search of algae, coral polyps, worms, and other small invertebrates.
Their continual munching keeps the coals free of algae and sediment, allowing them to breathe and maintain healthy growth.
These important reef-dwellers are usually found in the shallower parts of the dive sites, with few venturing below 18 - 20 metres.
We can often see small schools of white collar butterflyfish at all of the dive sites around Koh Lanta, with many other species usually seen in pairs. It?s unusual to see a solitary butterflyfish on the dive sites around Koh Lanta.
Butterflyfish are pelagic spawners, releasing hundreds of eggs into the water. The buoyant eggs float up to become part of the plankton layer, drifting with the currents until hatching.
Butterflyfish are found in all tropical waters around the world, though concentrated in the Indo-Pacific region.
The longfin bannerfish is often confused with the Moorish idol, however there are a few distinct differences.
The longfin bannerfish grows to 25 cm and has a white body with a pair of diagonal black bands. The dorsal, pectoral and tail fins are yellow. The first dorsal ray fin is white and elongate, creating a trailing filament. The snout has black spots and slightly stretched to the small mouth.
The longfin bannerfish is usually seen at the dive sites around Koh Lanta in small groups of 2 - 5 individuals and its diet includes zooplankton in the water column and bottom-dwelling invertebrates.
The singular bannerfish is the largest of the bannerfish, growing to 23 cm. The body and anal fin are coloured black, with the dorsal fin and tail fin being yellow.
The first dorsal fin ray is long and white. There is a small white stripe in front of the eye, and a large white bar behind the eye. This species has a noticeable bump on the nape (above the forehead).
The singular bannerfish feeds on coral polyps and prefers areas of rich coral growth. These fish are observed both solitary, and in small groups. A slightly less common species.
The phantom bannerfish has a white body background with two wide dark bands on the side, becoming brownish/yellowish as they converge toward the dorsal area.
The first rays of the dorsal fin are stretched in a short white feather-like filament. This species has a pair of horns just above the eyes, and further above, a prominent bony bump on the nape (above the forehead).
The phantom bannerfish is less commonly seen around the reef areas and grows to 17 cm. It can be observed, solitary, in pairs or small groups and can be found in a mixed algae and coral habitat.
The copperband butterflyfish is sometimes called the beaked coralfish and is common at all of our dive sites.
This fish has a long beak-like snout and a silvery-white body with three orange body bars, and one orange bar through the eye.
The rear dorsal fin has a dark eye-like spot designed to confuse would-be predators. There is a black bar on the base of the tail.
The copperband butterflyfish grows to 20 cm and is seen both solitary, and in pairs. It uses its long snout to pick out bottom dwelling creatures from cracks and crevices, including worms and small crustaceans.
The white collar butterflyfish, or ?redtail butterflyfish? grows to 18 cm. The body is generally dark grey, with lighter scale centers giving it a spotted appearance.
The tail base is bright red, followed by a black stripe and a whitish margin. There is a prominent, vertical white bar behind the eyes, a dark bar over the eyes, and another, smaller white bar in front of the eyes.
The white collar butterflyfish is often seen in pairs or aggregations and its diet includes soft and hard coral polyps.
The Lined Butterflyfish is the largest of all Butterflyfish, growing to 30 cm in length.
The body is white with vertical black lines and a broad yellow and black band at the rear of the body. There is a wide black eye-stripe which contains a white spot on the forehead. The dorsal, anal and tail fins are all yellow.
Whilst this species is generally uncommon, it is in fact quite common at the dive sites around Koh Lanta and is seen both solitary, and in pairs.
The Lined Butterflyfish diet includes both soft and hard coral polyps, anemones, algae and other invertebrates.
The Indian vagabond butterflyfish has a pearly white body with a chevron pattern of two sets of opposing diagonal dark lines and looks very similar to the vagabond butterflyfish.
There are several fine orange stripes across the forehead, and the tail is yellow. This species can grow to 20 cm in length and can be observed solitary, or in pairs and its home range is rubble or coral rich areas.
This species has a dark stripe through the eye, and another through the tail fin.
Unlike the similar looking vagabond and threadfin butterflyfishes, the Indian vagabond butterflyfish has a wide black band across the rear of the body which covers the rear dorsal fin.
The vagabond butterflyfish has a pearly white body with a chevron pattern of two sets of opposing diagonal dark lines.
There are several fine orange stripes across the forehead, and the tail is yellow. This species can grow to 23 cm in length and can be observed solitary, or in pairs.
This species has three dark stripes, one through the eye, one across the rear of the body, and one through the tail fin.
The vagabond butterflyfish can be distinguished from other similar looking species (Indian vagabond and threadfin butterflyfishes) by the narrow black band across rear body which does not cover the entire rear dorsal fin.
The eight-banded butterflyfish is a small species, growing to 12 cm. The body colour varies from white to a strong yellow colour.
Individuals with a lighter body colour may also have a dark spot on the base of the tail.
There are 7 black bars over the head and sides, one black bar in the middle of the snout, and another black bar which forms a strong margin on the end of the dorsal and anal fins. The tail also has a vertical black bar.
This species feeds on coral polyps and juveniles are usually found sheltering within the branches of staghorn corals. Adults are often seen in pairs.
The triangular butterflyfish has a roughly triangular shaped body and is generally grey with many pale yellow chevron markings and a dark triangle on the tail. This fish grows to 15 cm.
The triangular butterflyfish can often be found within the branches of staghorn corals (acropora corals) where it feeds on coral polyps. This is territorial species which normally only forms pairs for breeding.
The chevron butterflyfish has an elongate (stretched) white body with numerous black chevron markings, a black chevron band through the eye, a black tail with a yellow margin and may grow to 18 cm.
This species is territorial and will defend coral patches against other butterflyfish. The chevron butterflyfish can often be found in shallow areas around table and other staghorn corals, feeding on the coral polyps.
Juvenile chevron butterflyfishes have a broad black band extending from the rear of the dorsal fin to the rear of the anal fin a mostly yellow tail.
The Sunburst Butterflyfish has a generally yellow to yellowish-brown body with a whitish head and a diffuse vertical band on the forebody.
There is a dark vertical eye bar and the tip of the snout may also be black.
The Sunburst Butterflyfish has a yellow tail with a transparent tail fin margin. The scales may have lighter, or darker spots on them, giving the impression of rows or bands of spots running horizontally along the body.
The rear dorsal and anal fin may have a light margin.
The Sunburst Butterflyfish grows to 15 cm and can be observed singly or in pairs. Whilst a generally common butterflyfish, this species is rarely seen at the dive sites around Koh Lanta.
The diet includes soft coral polyps, algae and zooplankton.
The longnose butterflyfish has a yellow body and a distinct long snout with small mouth. The head is black on top, and silvery-white on the lower part. There is a dark spot on the anal fin, just below the base of the tail fin.
This species grows to 22 cm and is seen solitary and in small groups up to 5 individuals. Adults are usually seen in pairs and are territorial.
The diet consists of hydroids, fish eggs, small crustaceans, bristle-worm tentacles, and the tube feet of sea stars and sea cucumbers.
Can be confused with the ?big longnose butterflyfish? (Forcipiger longirostris) which has a longer snout and black spots on the white breast.
The Highfin Butterflyfish has a white body undercolour, with four brown to dark yellow bands, the first through the eye, the second from the front of the dorsal fin to the ventral fin, shortly followed by the third, and the final broad band at the rear of the body.
There is a dark band at the base of the tail fin and a dark spot at the front of the dorsal fin.
Very similar to the Orange-banded Coralfish (Coradion chrysozonus) but lacks the ocellated spot on the rear dorsal fin.
The Highfin Butterflyfish is a rare and poorly studied species, growing to 18 cm, but usually observed around 10 cm - 12 cm. Forms pairs during breeding.
The Orange-banded Coralfish is white, with a wide orange bar across the rear body, including the dorsal and anal fins. There are a pair of closely spaced orange to brown bars behind the head.
Similar to the Highfin Coralfish (Coradion altivelis. above), there is a dark band on the tail base and a dark spot on the forward dorsal fin, however this species has an ocellated spot on the rear dorsal fin.