Growth, feed conversion and faecal discharge of yellowtail kingfish (Seriola lalandi) fed three commercial diets

A study was undertaken to provide data on growth, feed conversion ratio (FCR) and faecal discharge of yellowtail kingfish (Seriola lalandi) fed three commercial diets used previously to culture this species in New Zealand. Fish were raised in tanks from 0.4 to 1.2 kg over the spring (water temperature 14-17 degrees C) and summer (17-22 degrees C) periods. There were considerable differences in volumetric and mass-specific feed intake, and energy intake amongst diets. Daily crude protein intake was similar amongst diets, although it increased from the cold (4.05-4.50 g protein kg(-1) day(-1)) to warm period (6.48-7.67 g protein kg(-1) day(-1)).The biological and economical FCR varied with diet (BFCR 1.22-2.17, EFCR 1.30-2.62), as did the cost of feed per unit biomass produced (Nz$2.38-3.78 kg(-1)). Growth rates were broadly similar amongst diets, and the warmer summer temperature period greatly improved both growth (increase from 0.51-0.64% to 1.18-1.23% mass gain day(-1)) and BFCR (decrease from 1.37-2.17 to 1.22-1.46). The Salmofood ESF diet resulted in only half of the faecal settleable solids and settleable total nitrogen (TN) and total phosphorus (TP) output compared with Skretting NME, which was in turn only half or less of that of Reliance SF.