Abstract
Jewel fish possess an innate cognitive mechanism which recognizes the two facing eyes of other fish. This mechanism functions adaptively in both a social and antipredator context, estimating the risks associated with other facing fish. Appearing about the time fry begin to school, this mechanism triggers a discriminative flight response to approaching models with two schematic facing eyes. Fry also tend to avoid the region in front of the parents from which they can see their two facing eyes.In a social context, juveniles and adults appear to be intimidated by facing adversaries as demonstrated by their energy expenditure during attacks and readiness to attack, respectively. These findings are discussed in relation to developmental plasticity of the innate cognitive mechanism and concomitant changes in risk assessment.