Something fishy

Is the Vietnamese river cobbler referred to in "Invasion of the Viet cod" (your report, 3 February) the same fish we were being warned against recently on the grounds that it is farmed in poisonous parts of the Mekong Delta? Perhaps processed meals which use it should have a health warning on the packet: "May contain traces of mercury and other poisonous substances".

BOB PEDEN

Causewayend Crescent

Aberchirder, Aberdeenshire