Exposure to the ultraviolet filter benzophenone-3 (BP3) interferes with social behaviour in male Siamese fighting fish

Oxybenzones like benzophenone-3 (BP3) are ultraviolet (UV) filters widely used in personal care products such as sunscreens. BP3 is currently receiving a great deal of attention because many of its properties, including high water solubility and potential to bioaccumulate, enable it to have damaging effects on aquatic ecosystems. One of these effects, the induction of coral bleaching, has led Hawaii to ban all sunscreens containing BP3. BP3 also appears to have endocrine-disrupting properties and has been found to affect animal physiology. However, behavioural consequences of BP3 exposure have yet to be thoroughly characterized. In the present study, we investigated the effects of BP3 on boldness, courtship and aggression in male Siamese fighting fish, Betta splendens, as little is known about the effects that BP3 has on fish social behaviour. To accomplish this, we assigned males to a treatment group (control, low, medium or high BP3 concentration) and completed individual (empty tank, novel environment and shoal) and social (courtship and aggression) behavioural assays before and after a 28-day exposure period. BP3 influenced the expression of social behaviours, with individual boldness generally unaffected. Changes in shoaling occurred regardless of BP3 concentration, while BP3-associated decreases in courtship and aggression were concentration dependent. Abnormal social behaviour may impede successful mating and alter territorial dynamics, with potentially heightened effects in species already experiencing other anthropogenic stressors.