Swallowtail Cardinalfish

The Swallowtail Cardinalfish (Verulux cypselurus) is a tropical marine species associated with reef environments, typically inhabiting depths ranging from 2 to 15 meters. It can reach a maximum length of 6 cm.

This species is characterized by an intermittent black stripe extending from the snout to the middle of the opercle, the absence of a black blotch on the caudal-fin base, and a semi-transparent body exhibiting a yellowish sheen on the head and belly. Additionally, there is a black spot or short stripe on the side of the snout, and each lobe of the caudal fin features a blackish submarginal band.

Swallowtail Cardinalfish commonly form large shoals among rocks or above coral formations within lagoon patch reefs. They often school alongside R. gracilis. At night, these fish disperse into mid-water to feed on plankton.

Furthermore, the species is noted for exhibiting distinct pairing behavior during courtship and spawning phases.