Northern pike
The northern pike is a relatively aggressive species, especially with regard to feeding. For example, when food sources are scarce, cannibalism develops, starting around five weeks in a small percentage of populations. This cannibalism occurs when the ratio of predator to prey is two to one. One can expect this because when food is scarce, Northern pike fight for survival, such as turning on smaller pike to feed; this is seen in other species such as tiger salamanders. Usually, pike tend to feed on smaller fish, such as the banded killifish. However, when pike exceed long, they feed on larger fish.