We used a computer model containing a flock of fish and a predator to evaluate the effect of energy on predator speed and success of various attack tactics. We also looked into predator confusability and tried to determine whether fish form flocks as a form of a defense mechanism. Results were obtained using a genetic algorithm. We simulated natural evolution of predators and prey, and came to conclusion that the best attack tactic is highly dependant on predator's method of confusability. Moreover, we showed flocking increases the chance of individual survival in certain attack tactics, while it decreases the chance of individual survival in others.