Conditioned alarm behavior in fathead minnows (Pimephales promelas) resulting from association of chemical alarm pheromone with a nonbiological visual stimulus

Fathead minnows (Pimephales promelas) adopt antipredator (alarm) behavior w hen they detect alarm pheromone released from an injured conspecific. This is an adaptive response since alarm pheromone is generally released only in the context of a predation event. Alarm reactions may also occur in respon se to chemical and visual stimuli that minnows learn to associate with rele ase of alarm pheromone. Here, we tested if fathead minnows can learn to ass ociate a nonbiological, visual stimulus with predation risk. Minnows were s imultaneously exposed to red light and conspecific alarm pheromone, inducin g an alarm reaction. When retested using red light alone, small shoals of m innows displayed an antipredator response: dashing movements and disorganiz ed swimming followed by decreased height in the water column and increased shoal cohesion. This resulted from a single-trial exposure to the combined cues and demonstrates a robust ecological mechanism by which minnows learn to recognize indicators of predation risk that may vary in space and time. However, learning to associate risk with biologically irrelevant stimuli ma y be an ecological liability. How minnows discern between relevant and irre levant stimuli in nature is not known.