This dataset gathers the names of 325 species of fish as well as their trophic category (8), habitat (9), abundance category (6) and minimum abundance (minimum number of individuals recorded per species and replicate), observed in 1990 across Yonge Reef (14°35’S latitude and 145°37’E longitude), an outer-shelf reef located in the northern part of the Great Barrier Reef, Australia. Underwater visual censuses (45 to 60 min) were performed in the nine habitats distinguished from the windward outer side to the leeward lagoon side, between 0.5 and 30 m deep. This dataset is a witness of the specific and trophic structure of fish assemblages across Yonge Reef in 1990 and will serve as a baseline for studies on the impacts of climate change on coral reef fish composition and functioning. Fig : Map of the study reef, Yonge Reef, in outer-shelf position on the northern Great Barrier Reef

List of variables Country = Name of country Reef = Name of the reef studied on the Great Barrier Reef Date = Date of observation Zone = Name of the geomophological zone of the reef (Outer slope, Reef flat, Inner slope) Site = Location of observation on the reef Depth Min (m) = Minimum depth of observation (m) Depth Max (m) = Maximum depth of observation (m) Habitat category = Category of habitats (9) Code Habitat = Code of habitat category (AGR = Acropora grandis zone; IPA = Isopora palifera zone; BOZ = Boulder zone; BRF = Back reef flat margin; DLS = Deep lagoon slope; DOS = Deep outer slope; ORF = Outer reef flat; SLS = Shallow lagoon slope; SOS = Shallow outer slope) Code Replicate = Initial numbering of observation replicate Fish family = Latin name of fish family or subfamily (Scaridae was kept as a family for simplicity following FishBase (2024) and not included in Labridae as the tribe Scarini as proposed by Hughes et al. (2023) Fish species = Latin name of genus and species of the fish recorded Trophic category (8) = code of diet category of the fish species (COR = Corallivores; CRU = Crustacivores; HMD = Herbivores, Microvores & Detritivores; IMA = Macroinvertivores; IMI = Microinvertivores; ISE = Sessiles Invertivores; PIS = Piscivores; PLK = Planktivores) (following Parravicini et al., 2020) Code Abundance (6) = Code of abundance category (1 = 1 individual; 2 = 2 - 5 individuals; 3 = 6 - 25 individuals; 4 = 26 - 125 individuals; 5 = 126 - 625 individuals; 6 = 626 - 3250 individuals) Min Abundance = Minimum number of individuals recorded per species in each abundance category References https://www.FishBase.org (2024) Hughes L.C., Nash C.M., White W.T., Westneat M.W. (2023) Concordance and discordance in the phylogenomics of the wrasses and parrotfishes (Teleostei: Labridae). Systematic Biology, 72: 530-543. Parravicini V., Casey J.M., Schiettekatte N.M.D., Brandl S.J., Pozas-Schacre C., Carlot J., Edgar G.J., Graham N.A.J., Harmelin-Vivien M., Kulbicki M., Strona G., Stuart-Smith R.D. (2020) Delineating reef fish trophic guilds with global gut content data synthesis and phylogeny. PloS Biology, 18(12): e3000702.