Theoretically present only in fish culture systems but may occur in certain canals. Does not reproduce naturally in the thermal and hydraulic conditions of the metropolitan rivers. Is produced in hatcheries for stocking in culture ponds and sometimes to control the vegetation in the canals (Ref. 30578). Its introduction is forbidden but encountered in Rhin, Loire, in the low part of Durance, in Sélune and some east rivers (Ref 40476). Also Ref. 2163.