Evaluation of bioball performance on physical and chemical parameters of water, hemological, immunogical and stress parameters and growth performance in Sterlet (Acipenser ruthenus)

Sterlet is one of the most valuable species of sturgeon that its population has declined in recent years. The bioball acts as a biological filter, which is a site for bacteria that can remove ammonia. This study was done for evaluation the effect of bioballs on physical and chemical parameters of water, growth performance, survival percentage and improvement of hemological and immunological factors and stress reduction of Sterlet in Dr. Keyvan Fisheries and Marine Technology Research Center of Chamkhaleh during 8 weeks. For this purpose, 150 Sterlet with initial weight of 120 gr were distributed in 15 fiberglass tanks that their capacity was 500 liters. 4 treatments including treatment 1 opened with bioball system, treatment 2 opened without bioball system, treatment 3 closed with bioball system and treatment 4 closed without bioball system were selected in 3 replications. During the experiment, physical and chemical parameters of water, hemological and immunological parameters, stress and growth performance were measured. Among growth indices, there was an increase in FCR, SGR, BWI and %BWI in treatments 1 and 3, which was significantly different from control treatments (P<0.05). Also, treatment 1 in terms of hemological factors, and treatments 1 and 3 in terms of immunological and stress indices were better. There was the lowest number of white blood cells and neutrophils and the highest number of red blood cells, hematocrit and MCV in treatment 1. The highest amount of total immunoglobulin and the lowest values of cortisol, lactate and glucose were observed in treatments 1 and 3. These results had significant difference with control treatments (P<0.05). Treatment 1 had better values than other treatments in terms of physical and chemical factors and pH, NO3, NH3, NH4 and TAN values were significantly different (P<0.05). In addition, treatment 3 had the highest bacterial count compared to other treatments (P<0.05). Therefore, treatments 1 and 3 can be selected as the best treatment based on their performance. Because they improved the conditions and increased the efficiency of system. Their existence improves living conditions, even if they are not directly used by aquatic animals.