Hematological Parameters of Red Tilapia (Oreochromis sp.) Fed Essential Oils of Mentha piperita after Challenge with Streptococcus agalactiae

The study focused on investigating the effectiveness of essential oils of peppermint (Mentha piperita) against Streptococcus agalactiae (bacteria causing hemorrhagic disease) in red tilapia with an infective concentration of 106 CFU/mL. The experiment was arranged with 2 control treatments: control 1 - commercial feed + no infection; control 2 -commercial feed + infection ofS. agalactiae; and 3 experimental treatments with essential oils concentrations of 0.125%; 0.25% and 0.5%. The study examined the blood cell morphology and physiological blood indices of red tilapia (including hemoglobin; hematocrit; red blood cells count; the total number of white blood cells and thrombocytes, erythrocyte size) at three stages: after 15 days of adding essential oils without infection; five days after infection; and ten days after infection. In this study, fish supplemented with peppermint essential oils stimulated the body to create immunity. However, concentrations of 0.125% and 0.25% showed higher results about this ability in the presence of bacteria while the concentration of 0.5% exhibited a higher antibacterial effect of essential oils.