Piranhas

Piranhas are small carnivorous fish that have become a large part of popular culture due to their aggressive feeding behavior - which has been exaggerated in countless media to portray them as man-eating monsters.

Much like sharks Piranhas in fiction are vicious, intelligent and extremely hungry - they also swarm their victims much as their real-world counterparts do: unlike the real-world Piranha however most fictional portrayals show them as actively hunting down humans.