Coral reef fishes form the most diverse vertebrate communities on earth, and hybridisation has traditionally been considered rare in this group. However, recent studies have revealed that hybridisation is common. The angelfishes have the greatest proportion (~30%) of hybridising species with 26 species reported to hybridise. Hybrids between three species in the genus Centropyge (C. flavissima, C. eibli and C. vrolikii) have been reported from Christmas Island. The aim of this study was to test the terrestrial theory that rarity of parent species and niche overlap are important factors promoting hybridisation and to test the fitness of the hybrids and parent species in terms of growth rates and reproduction. All species and their hybrids showed a strong niche overlap, they were more abundant at 20 m compare to 5 m and shared the same microhabitat within harems. Parent species and their hybrids also had similar diets that comprised a mix of green, red and brown algae. Hybrids showed to be viable and had similar fitness to their parent species, with no differences in growth rates and reproductive activity. This study provides empirical support that hybridisation in reef fishes conforms to terrestrial-based theories, and thus advances our understanding of the concept in coral reef systems.