The Effect of walnut shell on coloration of Koi fish (Cyprinus carpio)

In this study the effect of oral administration of green skin of walnuts on the growth and color of Koi fish (Cyprinus carpio) has been studied in 60 Koi fishof average weight of 1.50±0.06g and average length of 53.00±1.48mm in 3 treatments and 1 control and each with 3 replicates.Twelve aquariumsof 33×40×50 dimension were used. The control group had no food additives (basic food was fed). First treatment with food containing 0.1 percent, second treatment with food containing 0.2 per cent, third treatment with food containing 0.3 percent green skin of walnut was fed for 8 weeks (56day) breeding period. Every 20 days once, biometry including gravimetric and length measurement was done. Also, at the end of the period from each treatment, 3 fish were selected at to random.To asses the color change, the colorimetric system L*a*b* was used, using device CHROMA METER CR_40. There was no significant difference regarding all three factors. Generally, it can be concluded that the use of green skin of walnuts to fish food ration, cause no impact on some growth factors and as well as survival rate and food conversion rate, but the apparent color index impact was significanot(P≥0.05)