In ponds and lakes in the eastern United States, northern snakeheads are spreading. These fast-reproducing fish are native to Asia but have been accidentally introduced to ecosystems by humans on the East Coast. Adults grow up to a meter long. They feed on frogs and other fish, and they can survive out of water for hours, and even days, at a time. Scientists are now trying to figure out how to get rid of snakeheads, and in many areas it is illegal to own a live snakehead.

Why are these fish a problem for the East Coast ecosystem?

Snakebit: How to Fly Fish for Snakeheads - Fly Fisherman

a
They have the potential to crowd out or kill native fish species.
b
They have no natural predators to control the population.
c
They are poisonous to the local animal life.
d
They are not useful as a food source for humans.

a. They have the potential to crowd out or kill native fish species.