Examined interactions among newly recruited juvenile fishes and between juvenile fishes and transplanted resident damselfish on artificial reefs in St. Croix, US Virgin Islands. Two kinds of priority effects occurred: 1) recruitment of 3 species of settling juveniles significantly decreased in the presence of the territorial damselfish, and 2) prior settlement of a juvenile predator lowered successful recruitment of 2 juvenile prey species. The 1st effect increases determinism in the structure of coral reef fish assemblages, while the 2nd decreased their predictability.