FATHEAD MINNOWS, PIMEPHALES-PROMELAS, ACQUIRE PREDATOR RECOGNITION WHEN ALARM SUBSTANCE IS ASSOCIATED WITH THE SIGHT OF UNFAMILIAR FISH

To determine whether fathead minnows can learn to recognize potential predators through releaser-induced recognition learning, predator-naiv e minnows were simultaneously exposed to a neutral visual stimulus, th e sight of a northern pike, Esox lucius, or a goldfish, Carassius aura tus, paired with either minnow alarm substance (Schreckstoff) or water . Two days after this initial conditioning trial the visual stimuli we re presented alone and minnows previously conditioned with alarm subst ance exhibited an appropriate anti-predator response, while those cond itioned with water did not. The conditioned minnows were tested approx imately 2 months later and again the minnows that were previously cond itioned with alarm substance showed an appropriate anti-predator respo nse, while those conditioned with water did not. A comparison of the r eaction of minnows conditioned to a natural predator (the pike) and th ose conditioned to a non-piscivorous exotic (the goldfish) revealed a similar response intensity when tested 2 days after the initial condit ioning trial. However, approximately 2 months after the conditioning t rial, the reaction of minnows conditioned to pike was stronger than th at of minnows conditioned to goldfish, indicating that learning may be constrained to favour a response to the natural predator. Minnows tha t were initially conditioned to pike did not show an anti-predator res ponse to goldfish nor did minnows that were conditioned to goldfish re spond to pike, demonstrating that the learned response was specific to the species used in the conditioning trials and not to any large fish . These results extend the known benefits to alarm-signal receivers.