ENVIRONMENT chiefs are probing the deaths of fish in York's River Foss - but say the green duckweed which is currently carpeting the surface is not to blame. The Environment Agency says its ...

In fact, often the green covering is a collection of thousands of individual floating common duckweed plants. Contrary to the belief of no movement in the pond, duckweed grows at an astonishing rate.

Without it, pond owners may find their pond surfaces littered with dead fish. Duckweed can choke out a pond -- and the fish that live in it. Many ponds and lakes throughout the region can be seen ...