Incidences of gross morphological disorders in barbel (Barbus barbus) in three rivers in southern England

Incidences of gross morphological disorders in barbel (Barbus barbus) were investigated in three rivers in southern England. The water quality at the sites chosen for study on the Rivers Teme, Kennet and Lee were classified (according to the criteria of the National Water Council, 1978) as 1A, IB and 2, respectively. Generally, low levels of gross morphological abnormalities were seen in fish caught in the Teme and Kennet, although there were incidences of ocular disorders and extra barbules in 10 and 7%, respectively, of the Kennet fish. No tumours were found in barbel from the River Teme whereas there was a 2% incidence in the Kennet fish. In contrast barbel from the River Lee showed high levels of all the gross morphological disorders, especially haemorrhagic patches on the ventral surface (36%) and ocular disorders (72%). Tumours were seen in 25% of the barbel caught in the River Lee. The incidences of most of these gross morphological disorders did not appear to be age related. The possibility that these disorders were related to water quality is discussed.