Reproductive behavior of largemouth triplefin Ucla xenogrammus (Tripterygiidae) on reefs of Kuchierabu-jima Island, southern Japan

Reproductive behaviors of the largemouth triplefin Ucla xenogrammus were observed on reefs of Kuchierabu-jima Island, southern Japan. Males exclusively maintained home ranges including spawning sites on vertical walls of overhanging reefs where filamentous algae were densely distributed. Females visited a male's home range to release adhesive eggs into the dense algae. Males guarded multiple egg clutches, but rarely showed fanning behaviors or mouth cleaning to the eggs. Aquarium experiments showed that guarding males had no significant effect on egg development. Because of the favorable water exchange conditions around their spawning sites, male U. xenogrammus could avoid the energy costs for egg care.