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Very few groups of tropical marine fishes can boast such a multicolored body pattern like the butterflyfish. This marine family - scientific name Chaetodontidae, from the ancient Greek, it means "brus...
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Very few groups of tropical marine fishes can boast such a multicolored body pattern like the butterflyfish. This marine family - scientific name Chaetodontidae, from the ancient Greek, it means "brush-teeth" - includes 114 different species belonging to 10 genera, of which the genus Chaetodon is the most abundant in terms of number of species. The majority is found in the Tropical Indo-Pacific, while only four species occur in the eastern Pacific, and 13 species in the Atlantic.
The common name makes reference to the brightly colored body (mainly yellow, white and black but with many variations in terms of patterns) of many species. They typically have an "eye-spot," often located at the basis of the caudal fin, probably an anti-predatory adaptation (predators, especially in the confusing sensory world of coral reefs, may be induced to think that the fish is far larger than is it in reality. The eyespot can even reduce the probability of being bitten on the fins by small predators like fang-tooth blennies). Their disc shaped body, highly compressed, allows them to move easily through the cracks and crevices of the reef, and even if they are not particularly fast swimmers, are difficult prey for reef hunters.
The majority of species is about 20 cm long, with a pronounced jaw, which in some species like Forcipiger flavissimus can be about the 25% of the total body length. If the fish preys only on coral polyps, normally the snout is reduced, while for invertebrate feeders, due to the need to insert the mouth in very small holes or narrow crevices, becomes long and thin. Planktivorous species normally have protruding jaws to catch small, free-swimming prey.
Fig 1. The Big Longnose Butterflyfish (Forcipiger flavissimus) is one of the most common species available in the aquarium trade.
Fig 2. The Brown Butterflyfish (Chaetodon kleinii) is a good tank mate for aquarium beginners, thanks to the easy adaptation and feeding habits.
Fig 3: The Threadfin Butterflyfish (Chaetodon auriga) is another good member for big aquaria. Being territorial, if kept in small tanks, it may become aggressive.
Butterflyfish are present in tropical seas worldwide, often associated with coral reefs, many of them being obligate or facultative coral-feeders ('obligate' means they are able to feed only on coral polyps, while the facultative ones can even rely on other kind of food like algae, plankton or small invertebrates).
Coral feeders are strictly territorial, normally living in pairs that last for their life time, in a prolonged monogamy not so common in the animal world. There is not an evident sexual dimorphism: males and females generally look alike, even if sometimes the male is slightly bigger.
Butterflyfish reproduction starts with external fecundation, at least for the few species studied, and normally occurs at dawn, after some complex courtship behavior. Fecundated eggs will be released in the current, where they will remain until hatching. The presence of a drop of oil in their yolk sac guarantees that the newly hatched larvae will remain floating on the surface. When the larva arrives at around 5 mm of length (in a stage called 'tholichthys stage', unique among reef fishes) a bony armor covers the head, extending to form spines dorsally and ventrally. These pelagic larvae remain planktonic for two or more months, and after that period the armor is absorbed and the larva can settle at night, quickly transforming into juveniles.
Fig 4: An exemplum of a butterflyfish to be avoided. The Ornate Butterflyfish (Chaetodon ornatissimus) be cause it is an obligate coral-feeder.
Fig 5: The Blackened Butterflyfish (Chaetodon decussatus) is a possible good tank mate, even if it needs good water conditions and a large aquarium.
Fig 6: The Longfin Bannerfish (Heniochus acuminatus) is a peaceful butterflyfish and is easily kept in aquarium.
Juvenile butterflyfish can live in differe