Study on the effects of applying Garlic (Allium sativum) and Zataria multiflora extracts in control of prevalent ectoparasite (protozoa) in Persian sturgeon (Acipenser persicus) fingerling

Today, regarding the development of sturgeon rearing and importance of the aquatic health, it is necessary to apply natural material to combat pathogenic factors. Therefore, using medicinal plants is an excellent alternative instead of chemical material to control pathogenic factors. As, protozoan ectoparasites are one of the most important factors which have threatened sturgeon life, so this study carried out to determine lethal concentration of garlic (Allium sativum) and Zataria multiflora hydroalchoholic extracts on fingerlings of Persian sturgeon (Acipenser persicus) that the efficiency and the effective dose of theses extracts determined for controlling protozoan parasite naming Trichodina. Study on lethal concentration (LC50) of Zataria multiflora hydroalchoholic extract on fingerlings of Persian sturgeon showed that during 96h and 1h, the LC50 was 766.65 and 9933.44 mg/L, respectively. Also, LC50 of garlic extract during 96h and 1h was 1279.97 and 12624.08 mg/L, respectively. During experiments, all of physicochemical factors such as temperature, dissolved oxygen, pH, nitrite, nitrate, ammonium, electric conductivity and hardness measured in different treatments. Study on the pictures taken out from sections of gill, liver and skin of Persian sturgeon fingerlings (Acipenser persicus) showed that in different doses of garlic (Allium sativum) and Zataria multiflora hydroalchoholic extracts the LC50 was examined and some microscopic damages observed. They are hyperemia, adhesion in the gill filaments, cell necrosis, melanin pigments in gill primary filaments, cloudy swelling of hepatocytes, liver necrosis, hyperemia and increase in melanin pigments and melano macrophage centers in liver, moreover raise in melanofor and melanin, increase in mucous cells and lymphocyte also necrosis in epidermis observed in skin. Investigation on white blood cells (WBC) showed significant difference in lymphocyte and neutrophil numbers in different treatments (P0.05). During the experiments of LC50 for garlic and Zataria multiflora extracts, some abnormal behaviors such as increased irritability, abnormal swimming, severe contraction of muscles and scoliosis observed in high concentrations. Then, considering the results of the mentioned experiments, the study conducted on effective concentrations (EC50) of these extracts to combat Trichodina protozoan parasite. In this study the concentration of Zataria multiflora hydroalchoholic extract for final experiments was 200 to 600 mg/L. Therefore, it was determined for the first time that Zataria multiflora extract can be effective to combat Trichodina. The EC50 of Zataria multiflora extract for 1h bath is 437.62mg/L. Moreover, the concentration of garlic hydroalchoholic extract for final experiments set at 50 to 400 mg/L and the EC50 of garlic extract is 172.58 mg/L for 1h. In experiments of EC50, the differential counts of white blood cells (WBC) showed no significant difference in numbers of lymphocytes, monocytes and neutrophils in different treatments (P>0.05). But there is significant difference in numbers of eosinophils in different treatments (P