Rhinecanthus lunula, commonly known as the halfmoon picassofish, is a species of balistid triggerfish first described by John E. Randall and Roger C. Steene in 1983.

R. lunula can be differentiated from other Rhinecanthus species by its soft ray count and distinct coloration.

Anterior to the caudal peduncle is a curved black line which gives the species its name “lunula,” the Latin word for crescent.

[5] However, the fish seen in Egypt may have been misidentified, as other members of the Rhinecanthus, R. aculeatus and R. rectangulus, are known to exist in Africa.

[6] Rhinecanthus lunula are generally found in the outer areas of coral reefs 10 meters or deeper.