Fundamental problems of the anemonefish-sea anemone symbiosis were experimentally analyzed, especially at the period of the first encounter of symbionts, using naive juvenile anemonefish.

The results differed markedly from those of previous studies using adult fish. Naive juveniles of five Amphiprion species in the coastal region of Japan have an innate protection against their symbiotic anemones. Furthermore, juveniles of all four species examined were almost comprehensively protected from Amphiprion-symbiotic anemone species. Naive juveniles recognize their species-specific partner-anemones via chemical factors released by the latter, thus leading to a species-specific partnership. Visual cues do not play a large role in partner-recognition at the first encounter.

Possible reasons for the vast difference between the results of the present work and those of previous studies are discussed.