Rushing and spawning behavior of the Kidako moray Gymnothorax kidako

Abstract

This study investigated the reproductive behavior of the Kidako moray Gymnothorax kidako in Tateyama, Chiba, Japan and Enoshima Aquarium. Field observations on reproductive behavior were conducted for 19 pairs from 24 July to 23 August 2017, at depths from 13 m to 18 m. Among these pairs, two instances were observed where the male gripped the female’s snout in its mouth and rushed toward the water surface at 20:45 and 20:40. At Enoshima Aquarium on 8 August 2022, a male and a female spawned at 20:06 following similar behavior. These findings suggest that rushing is a pre-spawning behavior. Among the 19 pairs observed, males [80–100 cm in total length (TL)] were consistently larger than females (70–90 cm TL). However, a pair was interrupted when a small male, approximately 50 cm TL, rushed by gripping the female’s snout. This suggests that smaller males unable to establish pairs may participate in reproduction through sneaking.