Diving with Sea Chubs

Lanta Marine Life | kyphosidae

The 54 species of sea chubs have short heads, blunt snouts, and small mouths. They have strong, close-set teeth which are strangely shaped like hockey sticks, with two species often spotted on Koh Lanta dive trips.

There is a single, continuous dorsal fin which can be folded into a scaly groove. They have a forked tail and are usually a drab colour and may have some bluish or yellowish stripes.

Sea chubs are largely herbivorous, feeding mainly on algae, with others being carnivorous, feeding on invertebrates found on the seafloor, rocks and corals.

Very large schools can form in shallow rocky and coral reef areas for feeding, and we sometimes see this around the Koh Haa islands.

Members of this family sometimes gather in large numbers for pelagic spawning.

2 species found on this page:

Topsail Drummer (Kyphosus cinerascens)
Lowfin Drummer (Kyphosus vaigiensis)

Topsail Drummer

(Kyphosus cinerascens)

The Topsail Drummer, Kyphosus cinerascens, is found in small to large schools in shallower reef areas where there is abundant algae growth. Their diet consists of invertebrates, algae and seaweed. When feeding as a large school, they can quickly overwhelm territorial damselfishes and surgeonfishes.

Kyphosus cinerascens @ Koh Haa

The Topsail Drummer is typically a silvery-grey fish with fine horizontal lines along the side, a pale stripe on the cheek, and a large tail fin.

The fish has a small bump over the eyes and a more pointed, downward angled snout that other fish of the same genus.

The dorsal fin runs the length of the fish and appears 'connected' to the anal fin.

School of Topsail Drummers @ Koh Haa

Topsail Drummer @ Koh Haa

The Topsail Drummer is poisonous to humans and should not be eaten.

Lowfin Drummer

(Kyphosus vaigiensis)

Pair of Kyphosus vaigiensis @ Koh Haa

The Lowfin Drummer has two phases, the first having a silvery grey body with narrow bronze stripes, and the second phase with a darker body and numerous white spots. The Lowfin Drummer can rapidly change phase.

The rear dorsal fin is not elevated (as in the Topsail Drummer) and the outer edge of the anal fin is diagonal, aligning with the outer edge of the upper tail lobe.

The Lowfin Drummer grows to 45 cm and forms small to very large groups in rocky shore areas or above reef flats.