The butterflyfish are species of marine fish of the family, Chaetodontidae, found in tropical and subtropical waters, typically around coral reefs although some inhabit rocky reefs. A few species inhabit slightly colder waters, usually around rocky areas. As their name implies, they have bright colorful markings that resemble those of butterflies. They often have patterns with eye spots on them to confuse predators. They are often used as indicator species when studying the health of coral reefs. As the health of a reef declines, due to global warming and increased human activity, populations of butterflyfish decline dramatically. Over 100 different species of butterfly fish are found in the Atlantic Ocean, Indian Ocean and Pacific Ocean with some species being found in more than one ocean.
They are diurnal animals which feed during the day and rest in the coral reef at night. Most species feed on plankton, coral, sea anemones and occasionally small crustaceans and some, such as the long nosed butterfly fish, have extended mouths resembling long nosed pliers that have specialized teeth for feeding on minute prey hidden in crevices. At night, when hiding, they may exhibit remarkably different coloration to that seen during the day.
Those species feeding on corals tend to form pairs, which remain for life. They are highly territorial but on occasion join up with other fish when perusing the reef for food. Perhaps this is for the advantage of numbers to avoid being chased by other territorial fishes (such as damselfish). Some species form large shoals, feeding on localized concentrations of zoo-plankton.
They are often kept in marine aquariums but many species cannot be kept in tanks with coral, pipe worms and anemones, due to their habit of nipping on these organisms.
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