Wash your wellies – that's the message from ecologists at Bristol Zoo to people planning a walk along the riverbank.

Parents and children are being warned that if they don't clean their boots after treading in river or lake water, they might be spreading crayfish plague on their footwear.

Crayfish plague is a fungus-like disease which is harmless to people and animals but lethal to our native white-clawed crayfish. It can be spread by people as it attaches on to anything that gets wet in infected water – this can include wellies, walking boots, fishing tackle and nets.

Maddy Rees from Bristol Zoo, a spokeswoman for the South West Crayfish Project, said the public could take simple steps to protect the aquatic animal.

"We are urging people to help prevent the spread of the crayfish plague by simply cleaning and drying any equipment or footwear you get wet in our rivers and lakes. The drying is particularly important as any remaining moisture may enable the disease to survive," she said.

The South West Crayfish Project is a partnership led by the Bristol Conservation and Science Foundation – a sister organisation to Bristol Zoo Gardens – with the Avon Wildlife Trust, Environment Agency, Buglife and funded by Natural England, Biffaward and Bristol Water.