Spawning behavior of the collared knifefish, Cymolutes torquatus (Labridae) in Papua New Guinea

Abstract

A colony of about 10 males and nearly 50 females of Cymolutes torquatus was found living over a sandy substrate on the northwest coast of Normanby Island, Papua New Guinea at depths 14.6 to 18.3 m. Each male appeared to maintain a harem territory, approximately 10 to 14 m², with 4 or 5 females living in sub-units of this territory. Eleven matings of 4 males with 2 to 4 females each were observed on 9 and 10 April 1993. The broadcast spawning of C. torquatus is similar to that of razorfishes in the genus Xyrichtys, but in contrast to most tropical sand-dwelling fishes which mate at dawn or dusk, C. torquatus mated mid-morning between 9:38 to 10:50 h. Sexual dichromatism, color changes during mating, and cleaning of C. torquatus by juvenile Halichoeres zeylonicus are documented with color photographs.