ReadMe for data associated with 'Heterospecific aggression and dominance in a guild of coral-feeding fishes: the roles of dietary ecology and phylogeny'. All data were collected over the austral summer 2010/11 at Lizard Island (14º40’S, 145º27’E) on the northern Great Barrier Reef, Australia All questions regarding data files to be addressed to Shane Blowes (shane.blowes@my.jcu.edu.au). Three comma-delimited data files: 1) all_interactions_counts.csv: contains counts of all passive/aggressive interactions for all species pairs (including conspecific pairs). Each cell entry is a count of the number of passive/aggressive interactions. 2) aggression_analysis.csv: contains the data used for the analysis of aggression as presented in the manuscript. Column headings: Location: observations were recorded at 2 sites - North Reef and Palfrey Focal.spp: focal species of the observational period Competitor: competitor species Proximity: proximity of two individuals during interaction (categorical: < 30cm, < 1m) outcome: 0 = passive; 1 = aggressive diet.over: dietary overlap (Horn's similarity index) fdsp: focal dietary specialisation cdsp: competitor dietary specialisation phylo.simA: phylogenetic similarity c.diet.over: centred dietary overlap variable used in analysis c.fdsp: centred focal species variable used in analysis c.cdsp: centred competitor species variable used in analysis c.phylo.simA: centred phylogenetic similarity variable used in analysis 3) dominance_analysis.csv: data for analysis of behavioural dominance Column headings Focal.spp: focal species of observation Competitor: competitor species outcome: 0 = focal subordinate; 1 = focal dominant Focal.dietary.specialisation: focal dietary specialisation variable used in analysis.