Spawning rhythm, egg number, and spawning time of wild caught three-lined tonguefish, Cynoglossus abbreviatus, reared in tanks

Abstract

Spawning rhythm, number of eggs spawned, and spawning time were examined in wild caught three-lined tonguefish, Cynoglossus abbreviatus. Four females (total length: 312-355 mm) were reared separately with three males in each tank under natural temperature. The start of spawning and the spawning period differed between individuals. One female spawned 14-22 times during a single spawning season. During the spawning period, which began in late April and ended in early June, all females continued to spawn with frequencies of 44-81% across all days. The total number of eggs spawned during the entire spawning season and the maximum number of eggs spawned in 1 day were 334,000-521,000 and 45,000-53,000, respectively. These results indicate that the three-lined tonguefish is a multiple spawner. Mean egg diameter was 0.96-1.10 mm, and egg diameter decreased as the spawning season progressed. A significant correlation was detected between mean egg diameter and water temperature on the day of spawning. Moreover, spawning time in three-lined tonguefish maintained in tanks was estimated to occur between 14:00 and 0:00.