Shoaling and schooling
Dilution effect – A third hypothesis for an anti-predatory effect of fish schools is the ‘encounter dilution’ effect. The dilution effect is an elaboration of safety in numbers, and interacts with the confusion effect. A given predator attack will eat a smaller proportion of a large shoal than a small shoal. Hamilton proposed that animals aggregate because of a “selfish” avoidance of a predator and was thus a form of cover-seeking. Another formulation of the theory was given by Turner and Pitcher and was viewed as a combination of detection and attack probabilities.