Four Eyed Butterflyfish, Chaetodon capistratus

The Four-eyed Butterflyfish (Chaetodon capistratus) is a butterflyfish belonging to the family Chaetodontidae. It is alternatively called the Foureye Butterflyfish. This species can be found in the Western Atlantic from Massachusetts, USA and Bermuda to the West Indies and northern South America.

This species is the type species of Chaetodon. If this genus is split up as some have proposed, it will retain its present name like its closest relatives, which include the Banded Butterflyfish and the Spot-finned Butterflyfish.’

These butterflyfish are deep-bodied and laterally compressed, with a single dorsal fin and a small mouth with tiny and bristle-like teeth. The body is a light grey color, sometimes with a yellowish hue, and dark forward-pointing chevrons. The ventral fins are yellow in color.

The species gets its name from its common name from a large spot on the rear portion of each side of its body. This spot is surrounded by a brilliant white colored ring, looking much like an eye. A black vertical bar on the head runs through the true eye, making it difficult to see.

This pattern might result in a predator confusing the back of the fish for the front end. The fish’s initial instinct when threatened is to flee, putting the false eye spot closer to the predator than the head. Most predators aim for the eyes, and this false eye spot tricks the predator into believing that the fish will flee with its tail first. When escape isn’t possible, the fish will sometimes turn to face its aggressor, head lowered and spines fully erect, like a bull about to charge. This might serve as intimidation to the other animal or might remind the predator that the butterflyfish is much too spiny to make a comfortable meal.

The butterflyfish inhabits shallow inshore waters, where they feed on a variety of invertebrates, mainly zoantharians, polychaete worms, gorgonians, and tunicates. This fish is well known for its uncanny ability to swim in and around coral heads and reefs. They have the ability to find their way through the most intricate passages by swimming on its side or even upside down. Like its relatives, they mate for life and therefore will often be seen in pairs. They are one of few fish that mate for life.

Image Caption: Foureye butterflyfish (Chaetodon capistratus). Credit: Florida Keys National Marine Sanctuary/Wikipedia