The anemone fish, Amphiprion clarkii, is monogamous and spawns adhesive eggs in mass nearly at the same place, repeatedly during the warm months. The egg mass is laid on a flat hard substratu, protected by the tentacles of host sea anemone in one layer. This enables to count the total number of eggs in an egg mass after taking photography. These characteristics provide a good material to study seasonal change of egg production by a single female in temperature reef fishes. In the present study, egg numbers of clutches and egg sizes were monitored at two different places, one is at the southern end of Kyushu (Bohnotsu: 10 pairs) and the other was at the western end of Kyushu (Ushibuka: 12 pairs). The average water temperatures were slightly higher at B than U. Water temperature ranged 18.9-21.7℃ at B and 20.5-23.4℃ at U and the begeninng of spawning differed by pairs. The latest spawning also differed by pairs and confirmed to be at 25.7-29.3℃ at U, by pairs. The nuber of eggs spawned at one time by females was 1,925-5,989 at B and 483-5,535 at U were larger in the early part of spawning season and eggs sizes were apt to be larger during this period than the rest of spawning season. But, at B, where spawnnig season was slightly longer than U, the egg sizes showed a tendency to become larger again at the end of the spawing season.
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