Fig. 1. Feed intake, as percentage of body mass, of isolated juvenile rainbow trout after being transferred to observation aquaria. On day 7, the commercial feed was exchanged for a feed supplemented with L-tryptophan to a level eight times (TRP feed) that of the non-supplemented control feed (CTRL feed). Fish were fed to satiation, or to a maximum of 1.5% of the body mass. Values are means ± S.E.M. (days 1-7, N=96; days 8-10, N=48; days 11-17, N=32; days 18-35, N=16).