The Longfin Bannerfish -Heniochus acuminatus- is a striking and popular fish among divers, known for its distinctive appearance and friendly behavior. This small fish can often be seen at various dive sites around Koh Tao and primarily feeds on plankton. It reaches a maximum size of approximately 25 cm in length. At night, Longfin Bannerfish turn dark grey, with their white bands becoming less visible. When exposed to light, they quickly revert to their bright daytime colors. This rapid color change, which takes about a minute, adds an extra touch of excitement to night dives around Koh Tao.
Distinguishing Features
The Longfin Bannerfish features a white body with two black oblique bands. Its dorsal, tail, and pectoral fins are yellow, and a straight black line runs between its eyes. The dorsal filament, which is white, grows longer as the fish matures, trailing behind it while swimming. Juveniles and adults look very similar.
Behavior and Interaction
These friendly fish frequently approach divers, swimming around them without fear, and may not leave until you move away. Longfin Bannerfish are often found in pairs or small groups and are known for their graceful swimming patterns. They occasionally provide cleaning services to other fish, such as Big-eye Trevally.
Feeding Habits
Equipped with a long pointed mouth and bristle-like teeth, the Longfin Bannerfish is well-suited for rooting in crevices. They feed on zooplankton and bottom-dwelling invertebrates, including corals, and spend most of their time cruising the reef.
Reproduction
The Longfin Bannerfish is believed to spawn in pairs. They release their eggs into the open water, where the eggs, larvae, and fry drift with the current as pelagic egg scatterers. The juvenile fish eventually settle on the reef or seabed after drifting in the water column for a period.
Where to Find the Longfin Bannerfish on Koh Tao
You can spot the Longfin Bannerfish while scuba diving at several dive sites around Koh Tao,
including
White Rock,
Laem Thian,
Mango Bay,
Sattakut Wreck,
Lighthouse Bay,
Twin Peaks,
Aow Leuk,
Shark Island,
Japanese Gardens,
Tanote Bay,
Green Rock.
etc
