Coral reef fish communities of Uvea (Wallis and Futuna) fringing reefs, mid-lagoon reefs, inner barrier reefs and outer barrier reef slopes were studied along four transects using visual censuses during September 1999. A total of 194 fish species in 33 families were recorded. Labridae (34 species), Pomacentridae (33 species) and Chaetodontidae (23 species) were the main families. The composition of the species suggests that Uvea is located at a faunal junction between Pacific biogeographic regions. Mean density (2.5 fish/m2) was similar to other Pacific reef fish communities whereas mean biomass (43 g/m2) was within the lowest known values. Four fish assemblages were identified along an inshore-offshore gradient and related to substrate characteristics (live corals, dead corals, seagrass, algae and sand): one seagrass bed assemblage, two lagoon assemblages and one outer barrier reef slope assemblage. The major energy intake comes from lower levels of the trophic network, grazers (45.1% biomass) being the main trophic group. Other important trophic categories came from upper trophic levels: macro-carnivores (24.4%) and piscivores (14.5%). Micro-algae → grazers → piscivores was the most important energy path, before macro-invertebrates → macro-carnivores → piscivores. Plankton represented a minor resource (only 5% planktivores) during the study, which is unusual. Spatial variations in trophic networks occurred among the four fish assemblages with significant variations for grazers and macro-carnivores, and high variations for piscivores, planktivores and corallivores.