Referring to the various human and animal clinical response to consumption of reef fish, the authors precise the importance of ingested dose and the role of cumulative effects. They point out the arbitrary character of distinguishing poisonous and edible fish of the same species. At the light of these data they find ciguatoxin in edible fish from known latent ciguateric potential species in atoxic areas. Therefore ciguatoxin does appear as a natural biotoxin permanently produced in most of the polynesian coral reefs ecosystems. The occurence of clinical disorders by men and animals results from a sudden increase of its production following biological transitory modification of some coral reef biota.