Systemic infection with Uronema-like ciliates in farmed turbot, Scophthalmus maximus (L.)

Histophagous ciliates caused high mortality among turbot in a commercial fi sh farm in southern Norway. The ciliates spread systemically in fry (< 0.3 g). In the early stages of infection the ciliates were found in connective tissue in skin and fins, as well as in nervous tissue. In terminal stages t he whole organism was infected. In large turbot (500-1000 g), the ciliates were predominantly found in the central nervous system, causing liquefactio n of the nervous tissue. The ciliates were not identified to species but re sembled species in the genus Uronema (Scuticociliatida).