ABSTRACT
In its environment a fish encounters a variety of stimuli that can result in physical harm or death. Danger can come from abiotic sources. A fish may encounter waters that are too hot or too cold, waters that contain pollutants, waters with low dissolved oxygen, or waters in which ambient noise reduces hearing sensitivity. In addition, a fish may encounter biotic sources of danger, including poisonous plants, poisonous animals, and predators. To survive, fishes must escape or avoid such stimuli. The process of escape requires that the presence of the noxious stimulus be detected and that the fish remove itself from that situation. For example, a fish that enters water with a low oxygen content and moves to an area of a greater oxygen con tent would have escaped from an aversive situ ation. The process of avoidance requires the detection of stimuli that predict danger. Detec tion involves the animal’s sensory systems and a response that eliminates an encounter with the punishing stimulus. An example of avoidance behavior might involve a fish detecting a chemi cal stimulus that predicts the presence of a predator. In response, the prey fish seeks cover and thereby avoids a confrontation. This review focuses on three aspects of aversion learning in fishes. First, the questions of what stimuli fishes find aversive and how these stimuli are detected are addressed. Second, the interaction of avoid ance behavior with other behaviors is exam ined. Third, the variables that affect avoidance behavior in fishes are considered.
