The Spadefishes family (Ephippidae) are large, oval spade-shaped fish, with highly compressed (squashed flat) bodies, small mouths and matching dorsal and anal fins. There are two species of Spadefishes (batfishes) commonly found during Koh Lanta diving trips.
This well-known family includes the reef-dwelling genus Platax, the batfishes, which are often seen at dive sites around Koh Lanta, particularly Koh Haa and Hin Daeng.
With a maximum size of 50 - 60 cm, these can be curious fish, sometimes approaching and following divers, making them easy subjects for underwater photographers.
Batfish are generally shiny silver with areas of yellow and vertical brown or black banding. The eyes are often located in one of the vertical bands as a method of camouflage.
We sometimes see batfishes alone, but often we see them in small groups of two or three individuals, and occasionally in larger groups of 30 - 50+.
The reef-dwelling batfishes feed on algae, a wide variety of bottom dwelling invertebrates, and zooplankton. The diet also includes sponges, tunicates, bristle worms and soft gorgonian corals.
2 species found on this page.
Longfin Batfish
(Platax teira)
The longfin batfish is regularly seen at several of our dive sites, especially on the outside of Koh Haa Lagoon and at Hin Daeng.
This species has a silver body with a dark bar through the eye, though this may be faint. There is a second dark bar from the front of the dorsal fin to the ventral fin, and possibly a third dark bar behind this. The tail fin, anal fin and rear of dorsal fin may have a dark margin.
Longfin batfish can be easily distinguished from other types of batfish by the presence of a large dark blotch above the rear edge of the ventral fin.
Juvenile longfin batfish have exceptionally long ventral, dorsal, and anal fins compared to the size of their bodies.
Juvenile longfin batfish @ Koh Haa
Sub-adult longfin batfish @ Koh Haa
As they develop into sub-adults, the differences become less pronounced. Adult colourations can vary from very dark grey to very light grey, however the large dark blotch to the rear of the ventral fin is always present.
Larger adults will grow a low hump on the nape (above the forehead).
The longfin batfish grows to 41 cm, but more usually observed 30 - 35 cm, feeding on plankton, invertebrates and algae.
Schooling longfin batfish @ Hin Daeng
Dark variation longfin batfish @ Koh Haa
This species is often observed in small groups, but may occasionally form much larger groups.
Circular Batfish
(Platax orbicularis)
Platax orbicularis @ Koh Haa
Adult circular batfish have a silvery body with two dusky vertical bars, the first through the eye, and the second behind the head, connecting the front of the dorsal fin to the ventral fin. The pectoral fins are yellowish, and the ventral fins vary from dark to yellow.
The dorsal, anal and tail fins are yellowish with dark margins. There is a thicker black margin on the lower part of the anal fin. The base of the tail fin has a dusky vertical bar.
Circular batfishes are less common at our dive sites, but are most likely to be seen behind Koh Haa island Three, to the west, usually swimming close to the reef looking for food.
Sub-adult circular batfish @ Koh Haa
Adult circular batfish @ Koh Haa
This species usually has several small black spots on the sides, one of the unique identifying features of this species.
Juvenile Circular batfish are reddish-brown and resemble floating leaves drifting along the bottom, or at the surface with the current.
Adult Circular batfish grow to 28 cm and are often seen in pairs or small groups, but sometimes observed solitary.
