The Orbicular Batfish (Platax orbicularis) is a popular aquarium fish endemic to tropical waters of the Indian and Pacific Oceans.
Its body is almost disc-shaped, and very thin; the tail, about 20% of the body length, is fan-shaped and taller than it is long. Males can grow to up to 50cm in length, though aquarium specimens are generally much shorter. In the wild, the Orbicular Batfish is found in brackish or marine waters, usually around reefs, at depths from 5 to 30 metres. Its range extends from the Red Sea and East Africa in the east to the Tuamotu Islands in French Polynesia in the west, and from southern Japan in the north to northern Australia and New Caledonia. It has been recorded off the coast of Florida, though this may be the result of dumping of aquarium specimens.
Juvenile fish are solitary or live in small groups, among mangroves or other inner sheltered lagoons. Adults are found in more open waters and at greater depth.
Wikipedia on batfishes: They are spade-shaped, laterally compressed, and very symmetrical triangular dorsal and anal fins. They are 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. Scuba divers sometimes mistake them for angelfish, which are similar in shape but not closely related. Other genera in the family are characterized by long, trailing, pointed dorsal and anal fins.
Spadefish are generally considered to be an overfished group. Most of the individuals caught are small and young and are nowhere near the maximum size recorded for their species. A recent study in Current Biology (vol 16, p. 2434) has suggested that the batfish Platus pinnatus may play the role of a critical functional group in the Great Barrier Reef by eating seaweed that other herbivorous fish such as parrotfish and surgeonfish will not touch. Overgrowth of seaweed among corals occurs as a result of overfishing of large fish species and inhibits the ability of coral to support life.
Picture: Andaman&Nicobar Islands, India by Sami Salmenkivi