The effect of increasing non-protein energy level in a 40% protein diet on the voluntary feed intake (VFI) was investigated in juvenile rainbow trout (Oncorhynchus mykiss). Fish were fed to satiety using two different methods, hand feeding or time restricted self-feeding. Regardless of the feeding methods, the VFI ind the feed: gain ratio was always significantly higher for the fish fed the low energy diet than for those fed the high energy diet. In addition, no effect of the diet on the specific growth rate could be detected. It is concluded that fish were able to regulate with a great accuracy their feed intake when fed either by hand or by self-feeders. This regulation was precise enough to satisfy their energy needs and led fish fed the two different experimental diets to reach identical growth performance, regardless of the feeding technique.
