Effects of different water alkalinity levels on water properties, growth indices and hematological parameters of the Caspian Kutum fingerlings (Rutilus frisii, Kamensky, 1901)

This study aimed to investigate the effects of different alkalinity levels on growth performance, carcass analysis and blood parameters of kutum fingerlings. The examined fish samples were reared in five levels of alkalinity including a Hall water (control) with an alkalinity of 250 mg/l, 50% distilled water+50% Hall water (110 mg/l alkalinity), Hall water + 10 g sodium bicarbonate (soda, 350 mg/l alkalinity), Hall water + 20 g sodium bicarbonate (450 mg alkalinity), and Hall water + 30 g sodium bicarbonate (550 mg alkalinity) with three replications for 8 weeks. Results of the present study showed that with increased concentration of backing soda, levels of water pH, salinity, EC and TDS increased. Concentrations of ammonia and nitrate in water increased followed by increased concentration of backing soda and the lowest ammonia and nitrate levels were recorded in the treatment containing 110 mg/l CaCO3 and treatments with no backing soda addition, respectively (P<0.05). Contents of blood glucose and serum cortisol increased significantly with increasing soda-induced alkalinity. Changes in alkalinity level did not led to any significant changes in growth performance and feeding indices of the fingerlings. The increased level of backing soda significantly elevated the contents of hemoglobin, hematocrit, red and white blood cells. Results of carcass analysis detected significant differences among various treatments. Considering the non-significant differences among treatments with respect to growth indices, it can be concluded that this valuable species can be farmed in waters with alkali conditions similar to the present study.