Abstract
Reproductive ecology and ethology of Apogon notatus were studied in the shallow coastal waters of Shirahama and Sakura-jima, southern Japan. Male/female pairs began to separate from large aggregations as early as two months before the beginning of the spawning season. The pair stays at its home site during the daylight hours of each day, attacking and chasing other conspecifics approaching it. The female often displays “warping” to her male partner, but the latter exhibits no active display. In the early morning of the day of spawning, the female initiates the prespawning process, and after “parallel-circling” by the pair an egg mass is spawned in the parallel position between 11: 00 and 15: 00.The male takes the egg mass in his mouth within a few seconds after spawning.External fertilization occurs in the male's mouth within a few minutes after spawning, during the “rapid-circling” by the female.Both conspecifics and other fishes often interfere with the spawning process.Causal factors in the spawning process of A. notatus and the sex of the egg-incubating parent in Apogonidae are discussed.
