Comparative evaluation of commercial vegetable oil, fish oil, palm oil and groundnut oil as a lipid source in maturation and reproductive performance of fancy koi, Cyprinus carpio var. koi

Abstract

The present study to identify the best lipid source and optimum level of incorporation in the maturation diet of koi was carried out in 2 experimental trials. The first trial was conducted to evaluate the effect of selected lipid sources viz, commercial vegetable oil, fish oil, palm oil and groundnut oil on the reproductive performance of koi. The first trial was undertaken for 105 days and fed 35% crude protein diets and 7% lipid. The lipid sources used were Fish oil (T1), Palm oil (T2) and Groundnut oil (T3) and Commercial vegetable oil as the Control (C). The reproductive performance of the First trial experimental fish was assessed by the following factors viz, Gonadosomatic Index (GSI), fecundity, fertilization rate, hatching rate, and survival rate. GSI was found to be maximum in T2 (10.4 ± 2.80%) followed by T3 (10.15 ± 2.10%) and minimum in C (9.89 ± 1.22%). Maximum fecundity was observed in T3 (61,985 ± 2388) followed by other treatment animals viz T1 (55,160 ± 5988), T2 (52,839 ± 4636) and C (47,832 ± 1658). GSI was observed to be positively correlated with fertilization rate as observed by maximum fertilization rate (58.58 ± 2.35%) and hatching rate (50.91 ± 1.53%) in T3. Maximum survival rate was observed in T3 (20.51 ± 0.89%) followed by T2 (18.80 ± 1.06%), T1 (18.25 ± 1.06%) and C (15.89 ± 1.41%) during the ten days (upto early fry stage) nursery phase. The second trial was conducted until the animals in any treatment showed signs of good maturity, which was a maximum of 60 days. The best-performed lipid source, from the first trial, i.e., groundnut oil was taken and diets formulated at different lipid levels viz, 5% (T4), 7% (T5) and 10% (T6) with commercial vegetable oil (7%) as control diet (C). From the reproductive performance of the second trial experimental fish, it could be observed that T4 diet-fed fishes have shown significantly (p < 0.05) best reproductive performance compared to other dietary treatments. Thus, it could be concluded that groundnut oil performed better than other lipid sources, and the optimal level ranged from 5%–7% with quick subsequent maturation in 45 days after one spawning.