Scientists in Zimbabwe say a freshwater crayfish from Australia is breeding out of control in the northern Lake Kariba.
The crayfish is devouring the food sources of other fish and threatening the nation's entire aquatic ecosystem, according to reports.
Researchers at the Zimbabwe University say the red claw crayfish has no natural predators in the wild - crocodiles don't like them - and they produce clusters of eggs that hatch in abundance.
They were introduced a decade ago as part of a fish farming project.
Chief ecologist Crispen Phiri says the migrant crayfish population is infesting rivers, dams, ponds and tanks, because it eats everything in sight, including rotting vegetation and micro-organisms needed by fish and other aquatic life.