Effect of different concentrations of calcium of ambient water on hatching rate and ions content (Ca, K, Cu and Mn ) of rainbow trout egg in a water recirculating system

In this study, effects of four concentrations of waterborne calcium (8, 25, 50, 100 mg/l) on eyed egg percentage, hatching percentage and ions (Ca, K, Cu and Mn) uptake of rainbow trout eggs in a water recirculating system were determined. Twelve experimental units, with the capacity of holding 45 liter of water were used and 21g egg introduced in each one. Different concentrations of ions (Ca,Na,K,Mg,P,Fe,Cu,Zn,Mn) in treatments were prepared by adding analytical salts (Merck) into double-de-ionized distilled water. Dissolved oxygen and water temperature variations during incubation were 9.80-11.11mg/l and 7.5-9 ºC respectively. The eyed egg percentage was not significantly (P>0.05) different among treatments. The hatching percentage of eggs were significantly (P