Effects of dietary replacement of fish oil with canola oil in the diet of juvenile common carp, Cyprinus carpio on growth performance and feeding utilization of body and diet economic index

This study was designed to determine the effects of dietary replacement of fish oil with canola oil on growth performance، feed efficiency of body and Economic indices of experimental diets of juvenile Common carp (Cyprinus carpio). During the experiment 270 juvenile fish with an average initial weight of 16. 24 ± 0. 10g were randomly distributed in 18 well aerated cylindrical polyethylene tanks (15 fish per 300L capacity tank). Experimental fish were fed with six isonitrogenous (crude protein content 30. 02 percent)، isolipidic (crude lipid content 8. 77 percent) and isoenergetic (1. 184 MJ/kg) diets consisting of six levels of dietary replacement of fish oil (FO) with canola oil (CO) (100FO، 80FO20CO، 60FO40CO، 40FO60CO، 20FO80CO and 100 CO)، for 56 days. One-way ANOVA showed no significant difference (P>0. 05)، in growth performance، feed efficiency parameters، hepatosomatic index (HSI)، cardiosomatic index، condition factor and economic index between the experimental treatments. However، ANOVA showed a significant difference in survival rates، net lipid utilization (NLU) and the viscerosomatic index (VSI) (P <0/05) While the highest and lowest VSI and NLU were recorded in the first and sixth treatments، respectively، Moreover، highest and lowest viscerosomatic index were observed in the sixth and the fourth dietary treatments، respectively. Based on the variation in growth and feeding indices it could be presumed that incase of longer duration of the experiments significant variation in growth and feeding indices would have been observed that maybe due to the imbalance of essential fatty acids in fifth and sixth dietary treatment and failure to provide complete body needs for fatty acids. Moreover، taking into consideration the poor results obtained in the condition and economic indices of fifth and sixth treatments، it could be concluded that the most suitable dietary treatment for feeding juvenile common carp is replacement of 60% of fish oil with canola oil.