抄録
Abstract We conducted underwater observations on courtship and spawning be-haviors of the tetrarogidid fish, Hypodytes rubripinnis in Kyushu Island, Japan. The reproductive behavior and seasonal changes of gonad somatic index on col-lected specimens showed that spawning occurred from late April to early August. Individuals of various sizes in both sexes reproduced in the study area. About 90 min before sunset, a male courted a female actively with several patterns of be-haviors such as male's lying by a female in a side-by-side position, display of his lateral side around a female, and male's riding on a female back. Finally, the pair swam toward 20 to 100 cm above the bottom to release gametes. Spawning time was around sunset. The average egg number in each spawning was about 1600. Upward rush of the pair to the middle water occurred very quickly. Frequent sneaking behavior by another male was also observed.
