The natural spawning behavior of the kissing loach, an endangered species of Botiidae, was investigated in the wild in early June for two years in relation to several environmental factors. Kissing loaches spawned in temporary waters after elevation in water level. All spawnings observed (n=163) occurred within 3-5.5 hours from late afternoon to night after formation of the temporary water. These spawnings were performed by one female and one (71%) or two (29%) males in densely vegetated lentic waters. The female and following male(s) swam into dense grasses, where they vibrated to spawn intermittently. After the vibration continuing for 3-20 seconds, they moved to other parts of the dense grassy area and began vibration again. This sequence of spawning behavior was usually repeated several times, and the eggs were thus scattered widely. The spawning behavior and the rapid larval development of this species appear to be adaptations for the use of temporary waters as a spawning ground. The rise in water level and the consequent formation of temporary waters appear to be crucial triggers for reproduction of the kissing loach.