Behavioural fever, fish welfare and what farmers and fishers know

Abstract

In this article we first describe briefly how, like other ectotherms, wild fish promote effective functioning (for example, digestion and reproductive maturation) by moving through the temperature gradients that they experience in their natural habitats (showing behavioural thermoregulation). We then look in more detail at one particular example of behavioural thermoregulation in fish, specifically the phenomenon of behavioural fever; this refers to an acute, reversible increase in preferred water temperature in response to pathogen recognition. Behavioural fever promotes survival by stimulating an effective immune response to the responsible pathogen. An on-going project is described that explores the possibility of using this capacity for behavioural fever to promote disease resistance in fish in Nile tilapia farms. This project involved intensive discussion with experienced tilapia farmers, during which it emerged that a number of these farmers already knew how their fish make use of thermal gradients. Using this observation as a pivot, we then switch to consideration of the extensive non-scientific, traditional knowledge of fish ethology possessed by experienced fish farmers and fishers and discuss possible implications for fish culture.