Butterflyfish

Butterflyfish are small, brightly patterned reef fish named for their bold colours. In this app the group includes the Threadfin butterflyfish, Raccoon butterflyfish, and Chevron butterflyfish.

Butterflyfish look like small angelfish, but they lack the sharp spine on the gill cover that angelfish have. To tell members apart, look at colour pattern, such as bands, spots, or eyespots, and at snout shape, since some species have a long, thin snout for reaching into crevices.

Butterflyfish have a flat, disc-shaped body and a continuous fin along the back. Their tail is rounded or flat-edged, never forked. Most are 12 to 22 centimetres long, though the largest species reach 30 centimetres. Many have eyespots or a dark band across the eye, and colours range from bold black, white, blue, red, orange, and yellow to plainer tones.

Butterflyfish live on coral reefs across the tropical Atlantic, Indian, and Pacific Oceans. Most stay in water shallower than 18 metres, though a few species go as deep as 180 metres.

Butterflyfish are active by day and hide in reef cracks at night, when their colours change. Species that eat coral are territorial and often form pairs that guard one area, while species that eat plankton gather in large groups.

Most butterflyfish eat coral polyps and sea anemones. Some species instead feed on plankton drifting above the reef.

Butterflyfish release many small, buoyant eggs into open water, where they drift with the plankton until they hatch. The young pass through a stage where bony plates cover the head before they take on their adult shape.

harmless to humans

• 

  Banded Butterflyfish

  Chaetodon striatus

• 

  Blackback butterflyfish

  Chaetodon melannotus

• 

  Chevron butterflyfish

  Chaetodon trifascialis

• 

  Copperband butterflyfish

  Chelmon rostratus

• 

  Four-eyed Butterflyfish

  Chaetodon capistratus

• 

  Longnose butterfly fish

  Forcipiger flavissimus