Standard Talk (15 mins) Australian Society for Fish Biology Conference 2022

Neophobic behavioural responses of parasitised fish to a potential predator and baited hook (#121)

Raf Freire 1 , Leia Rogers 1 , Darcy Creece 1 , Shokoofeh Shamsi 1
  1. Gulbali Institute, Charles Sturt University, Wagga Wagga, NSW, Australia

Many juvenile fish show essential avoidance of predators but are also faced with the need to show risky asset-acquiring behaviour such as trying new food sources. Here, we investigated the links between parasite infection, predator avoidance and neophobia towards a novel food presented on a baited hook in fish. Juvenile Spangled perch (Leipotherapon unicolor) undertook two behavioural tests in our laboratory, before being dissected and examined for external and internal parasites. We used an adapted conditioned place avoidance (CPA) paradigm to examine avoidance of the side of the tank where a larger predator fish was visible and in a separate test, we examined neophobia of a baited hook. Of the 69 Spangled perch studied, 27% of fish were uninfected and at least one of nematodes, metazoa or Monogenea were found in the remaining fish. Fish spent less time in the side of the tank after encountering the predator there, than before encounters, indicating that fish can learn to avoid locations where predators were previously observed. Fish infected with metazoa and camallanid nematodes avoided entering the side of the tank with the predator compared to uninfected fish, suggesting increased predator avoidance in infected fish. However, both metazoa-infected and camallanus-infected fish bit the baited hook sooner than uninfected fish, indicating less neophobia of the baited hook in fish with these infections. Additionally, fish infected with Monogenea spent less time in the side of the tank with the predator fish, perhaps indicating reduced predator inspection. Avoidance of predators yet reduced neophobia to novel foods in some infected fish suggest that parasites do not exert a general, overall, effect on risk aversiveness. Instead, changes in neophobic behaviour appear complex and we discuss the possibility that parasite-induced changes in fish behaviour may be modulated by altered hunger levels and reduced locomotion brought about by illness.