The Red Sea Bannerfish (Heniochus intermedius) is a Perciform fish which is found in waters around Africa and the Middle East. This fish is pale yellow below and white above, with two broad diagonal black bands, up to 20 cm in length. The butterflyfish are a group of conspicuous tropical marine fish of the family Chaetodontidae; the bannerfish and coralfish are also included in this group. il pesce farfalla bandiera
Butterflyfish mostly range from 12 to 22 cm. length. The largest species, the lined butterflyfish and the saddle butterflyfish, C. ephippium, grow to 30 cm. The common name references the brightly coloured and strikingly patterned bodies of many species, bearing shades of black, white, blue, red, orange, and yellow. Other species are dull in colour. Many have eyespots on their flanks and dark bands across their eyes, not unlike the patterns seen on butterfly wings. Their deep,laterally narrow bodies are easily noticed through the profusion of reef life. The conspicuous coloration of butterflyfish may be intended for interspecies communication. Butterflyfish have uninterrupted dorsal fin with tail fins that may be rounded or truncated, but are never forked.
Generally diurnal and frequenting waters less than 18 m. deep (though some species descend to 180 m.), butterflyfish stick to particular home ranges. These corallivores are especially territorial, forming pairs and staking claim to a specific coral head. Contrastingly, the zooplankton feeders form large conspecific groups. By night, butterflyfish hide in reef crevices and exhibit markedly different coloration.
Their coloration also makes them popular aquarium fish. However, most species feed on coral polyps and sea anemones. Balancing the relative populations of prey and predator is complex, leading hobby aquarists to focus on the few generalists and specialist zooplankton feeders.
Butterflyfish are pelagic spawners; that is, they release many buoyant eggs into the water, which become part of the plankton, floating with the currents until hatching. The fry go through a tholichthys stage, wherein the body of the post larval fish is covered in large, bony plates extending from the head. They lose their bony plates as they mature.
(extract from Wikipedia)