Feeding level is a major factor in maximising feed efficiency and reducing effluent pollution in fish farming. In previous studies on stocking density, feeding levels used in normal commercial practice were employed. The results tended to suggest that these levels were too high for maximum feed efficiency. Consequently a series of trials was undertaken at different times of year to study the effect of feeding level, at a range of water temperatures, on growth and feed efficiency.
Three 21 d trials were conducted in early winter, spring and late summer, to avail of different water temperatures and dissolved oxygen concentrations. Four different feeding levels (22, 19, 16 and 13 g/kg bodyweight) were used in each trial. Trials one and two had three replicates of the four levels and trial three had two replicates. Identical adjacent ponds (18 m3) were used in each trial and were randomised for feeding level. Initial weights were 30, 50 and 20 g in trials one, two and three respectively.