An 8-week feeding trial was conducted to determine the optimum dietary protein and lipid levels for growth, feed utilization and body composition of goldfish, Carassius auratus juveniles (1.66 ± 0.018 g). Six diets containing two protein levels (300 and 400 g/kg) and three lipid levels (40, 80 and 120 g/kg) were formulated. Fifteen fish were randomly allotted to 18 aquaria (0.6 × 0.3 × 0.45 m) and fed to apparent satiation. The results showed that weight gain and specific growth rate (SGR) increased in response to higher dietary proteins with highest weight gain and SGR recorded in diet containing 400 g/kg protein with 80 g/kg lipid. Both feed intake (FI) and protein efficiency ratio (PER) were dependent on dietary protein and lipid level (P less than 0.05). Lipid retention (LR) was negatively correlated while hepatosomatic index (HSI) and viscerosomatic index (VSI) was positively correlated with dietary lipid levels. Whole body protein content decreased (P less than 0.05) while, lipid content increased with increasing dietary lipid at each protein level. Second-order polynomial regression also revealed diet containing 400 g/kg protein level and 80 g/kg lipid level optimal for the growth and feed utilization of juvenile goldfish, C. auratus.

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To establish an effective feeding regime for Carassius auratus, this experiment investigated the effects of feeding ration and feeding frequency on growth, feed utilization and body composition in juvenile C. auratus (Initial weight: 1.66 ± 0.018 g). A 4 × 4 experimental design of four ration sizes (2, 3, 4 and 5% body weight per day [BW/day]) with four feeding frequencies (1, 2, 3 and 4 meals/day) was carried out over 8 weeks with three replicates per treatment. The results showed that weight gain and specific growth rate (SGR) increased significantly (P less than 0.05) with the feeding ration from 2% BW/day to 3% BW/day and feeding frequency from 1 meal/day to 4 meals/day. Similarly feed conversion ratio (FCR) and protein efficiency ratio (PER) were significantly better (P less than 0.05) at feeding ration of 3% BW/day than 4 and 5% BW/day at 4 meals/day than 1, 2 or 3 meals/day. SGR, FCR and PER further reduced when feeding ration was increased beyond 3% BW/day. Lipid content improved with the increased feeding frequency at all feeding rations, however feeding frequency did not exhibit a significant effect on crude protein level (P>0.05). Moisture content of body showed an opposite trend to lipid content and decreased with increase in feeding frequency. In conclusion, feeding ration of 3% BW/day and feeding frequency of 4 meals/ day was found to be better for maximal growth and feed utilization of young ones of C. auratus.