The peacock grouper (Cephalopholis argus) was intentionally introduced to the Hawaiian coastal waters 50 years ago to enhance the local fisheries. Following introduction, this species spread rapidly and became extremely abundant. A comparison of the metazoan parasite community of C. argus was performed between its native range (Moorea Island, French Polynesia) and its introduced range (Oahu and Big Island, Hawaii). Polynesian groupers were infected with a highly diversified parasite community whereas Hawaiian groupers exhibited a depauperate ensemble of parasite species, C. argus having lost most of the parasites common in their native range. Interestingly, the grouper has not acquired new parasites present in Hawaiian waters. This study provides the first field evidence of significant parasite release in a wild but previously introduced fish in coral reefs and is discussed in relation to the Enemy-Release Hypothesis which has never been assessed in those ecosystems.