The Parks Trust made the announcement yesterday afternoon.
A statement said: 'With immediate effect Ashland Lake is an Aquatic Animal Disease Control Zone for Koi Herpesvirus Disease.'
All fishing has been suspended at the lake, and the disease is not transferable to humans.
One of the major effects is that the disease creates a debilitating mucus on the gills. A
lthough The Parks Trust doesn't believe the disease can be passed to animals, they are recommending that animals do not go into the lake.