There are more than 100 different species of butterfly fish found distributed throughout the Atlantic, Indian and Pacific oceans, meaning that the butterfly fish is a salt-water species of (marine) fish.
The average butterfly fish is fairly small and generally grows to around 4 or 5 inches in length. Some species of the butterfly fish however, are known to grow to 8 inches (20 cm) long and some butterfly fish individuals have been known to grow to 30 cm in length.
The butterfly fish can live for up to 10 years in a well kept aquarium but will only reach about 7 years old in the wild. The butterfly fish is a difficult fish to keep as they need very specific water conditions that need regular and close monitoring and so the butterfly fish is only found in specific water conditions in the wild.
The butterfly fish is most closely related to the marine angelfish which is similar in colour but the marine angelfish is often much larger in size than the butterfly fish. Butterfly fish can be distinguished from angelfish by the dark spots on their bodies, dark bands around their eyes and the fact that the mouth of the butterfly fish is more pointed than the mouth of the angelfish.
Butterfly fish are diurnal animals which means that they are feeding during the day and resting in the coral during the night. Most species of butterfly fish feed on the plankton in the water, coral and sea anemones and occasionally snack on small crustaceans . Those butterfly fish fish that primarily feed on the plankton in the water are generally the smaller species of butterfly fish and can be seen in large groups. The larger species of butterfly fish are fairly solitary or stay with their mating partner.
Butterfly fish are preyed upon by a number of large predators including fish such as snappers, eels and sharks. Due to the fact that the butterfly fish is small in size, it is able to tuck itself into crevices in the coral in order to escape danger and prevent itself from being eaten.
Butterfly fish form mating pairs that they remain with for life. Butterfly fish release their eggs into the water which form part of the plankton (it is because of this that many butterfly fish eggs are accidentally eaten by animals that live on plankton). When the eggs hatch, the baby butterfly fish (known as fry) develop armoured plates on their bodies to protect them when they are so vulnerable. As the butterfly fish gets, older these plates disappear. Butterfly fish have an average lifespan of 8 to 10 years although some of the larger butterfly fish species are known to get to much older.
Today, the butterfly fish is considered to be an endangered animal mainly as butterfly fish populations have been threatened due to water pollution and habitat loss. The destruction of coral reefs occurs mainly from boats, and without their coral habitat, the butterfly fish find it difficult to survive as they have less food and are also more exposed to predators.