One of the 100 most invasive species in the world the Nile perch was introduced to East Africa's Lake Victoria in the 1950s, and has wreaked environmental havoc ever since. It's illegal to possess or sell in some parts of the world, and is thought to have caused the extinction or endangering of hundreds of native species in Lake Victoria.

After the fish eliminated much of the algae-eating population, the lake became choked with algae. The perch has also increased local demand for firewood, because their higher fat content drives people to smoke them rather than dry them. Adult perch can grow to weigh more than 440 pounds, and are fierce predators that feed on insects, crustaceans, and other fish--even those of its own species.

Pictured here are dead Nile perch on a butcher table waiting for transport to local markets.