Bolton-Warberg reviewed the growing body of evidence on cleaner fish — principally ballan wrasse, goldsinny wrasse, corkwing wrasse, and lumpfish — as biological control agents in Atlantic salmon farming. The paper assessed feeding preferences, optimal stocking densities, temperature tolerance ranges, and husbandry requirements for each species, drawing on data from commercial deployments in Norway, Scotland, and Ireland.
The review confirmed that cleaner fish provide measurable reductions in both sea lice burdens and soft biofouling on cage nets, with lumpfish proving more effective in colder northern waters and wrasse species performing better at moderate temperatures. Against biofouling specifically, cleaner fish were documented consuming hydroids, small mussels, tunicates, and filamentous algae, extending the interval between mechanical net cleans by 30 to 50 percent at well-managed sites. However, the author cautioned that cleaner fish cannot remove cemented adult barnacles or calcareous tubeworms, and welfare concerns around overwintering mortality in lumpfish remain unresolved.
For a practical guide to selecting the right species, see wrasse versus lumpfish. The solutions comparison tool positions biological control alongside other methods, and the article on cleaner fish in salmon cage maintenance discusses real-world implementation strategies.