Mobile cleaning stations: trevally scrape on sharks in a tropical reefscape

Inter-species scraping has been reported between sharks and some teleost fish species to reduce ectoparasite loads and thereby increase fish health in an otherwise featureless pelagic environment. Here we report observations of interspecific scraping behaviour in reef environments between three species of trevally and three species of shark in the Seychelles Archipelago. These include the first scraping interactions for bull sharks Carcharhinus leucas and tiger sharks Galeocerdo cuvier observed in the wild. The interactions occurred despite the availability of cleaning stations and rough substrates suitable for self-scraping. These observations further our understanding of inter-species cleaning relationships in reef-associated fish and sharks, and suggest that sharks may play a role in supporting reef fish health.