Film shows testing of effluent levels on fish in laboratory and in the field. River scenes, fishing trout and salmon, using seine nets and coarse fishing. Water sample taken to London to Ministry of Agriculture, Fisheries and Food Fresh Water Fisheries Division, West Block. Water samples are tested by using Harlequin fish from Malaya [Malaysia]. Diagram of apparatus used. Field testing of water shown. Ministry of Agriculture, Fisheries and Food Fisheries Department
