Attempts are being made to remove a fast-breeding fish found in two east Devon lakes amid fears it could wipe out the indigenous fish population.
The gudgeon can spread a parasite deadly to native species
Topmouth Gudgeon, a small Asiatic member of the carp family, appeared in mainland Europe in the 1960s.
The Environment Agency is now trying to eradicate it from lakes at Bicton.
The fish, which can carry a parasite that can kill off most other fish, will be removed on Thursday using a process called electro-fishing.
The technique involves putting an electric current into the water to temporarily stun the fish.
Bicton is thought to be the only site in Devon with a population of the fish, which matures at one-year-old and can breed up to four times a year.
"We are keen to take action to eradicate them," said Dave Brogden from the Environment Agency.
"They pose a very real risk to our native fish. It is important we act now."
The Agency has already successfully removed the species from two sites in the north of England and one in the Midlands.