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The feeding behaviour, growth and feed conversion ratio (FCR) of cage-held Atlantic salmon parr (Salmo salar L.) were studied when in 576 m 3 (12 m  12 m  4 m) commercial freshwater cages under ambient water temperature (8.84 AE 3.53 1C) and photoperiod (11.02 AE 2.05 h) for 205 days. The e¡ect of feeding regime on ¢n damage was also investigated. Six groups (n 5 31234 AE 2051 ¢sh group À1 , initial stocking density 1.25 AE 0.14 kg m À 3 ) were fed to satiation using either (a) an imposed regime involving scheduled, ¢xed ration feeding every 10 min from dawn till dusk or (b) on demand from dawn till dusk using commercial interactive feedback systems. During feeding, there were no signi¢cant di¡erences in aggression although swimming speeds and turning angles were signi¢cantly higher in ¢sh under the imposed regime. On-demand feeding signi¢cantly reduced the incidence of dorsal ¢n damage. There was no clear relationship between ¢sh size, feed regime and the incidence of ¢n damage until 1 week before the ¢sh were transferred to marine cages, when the smallest ¢sh under each feeding regime had the highest incidence of ¢n damage. Interestingly, growth did not di¡er between regimes, but ¢sh under the imposed regime were signi¢cantly overfed and achieved higher FCRs.

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