Effect of Hyssopus officinalis extract dietary supplementation on serological parameters, growth indices, and survival of common carp (Cyprinus carpio) against Aeromonas hydrophila

The hyssop (Hyssopus officinalis) is known as a medicinal plant with antimicrobial and antioxidant properties. Despite a long history of medicinal use of H. officinalis, very few studies have been reported on the effect of H. officinalis on fish. Thus, the present study tried to investigate the effects of H. officinalis extract as a food supplement on serological parameters, growth indices, and survival of common carp (Cyprinus carpio) against Aeromonas hydrophila. For this purpose, the fish were divided into four treatments and fed with concentrations of 0, 250, 500, and 750 mg/kg H. officinalis extract in the diet for 60 days. The results revealed that the growth indices, including weight gain, length gain, specific growth rate (SGR), and food conversion ratio (FCR) in the treatments supplemented with H. officinalis extract, have no significant difference compared to the control treatment. Serological analysis showed that total protein increased in the treatments supplemented with H. officinalis extract, which was signi?cantly different in 500 and 750 mg/kg H. officinalis extract compared to the other treatments. Immunoglobulin signi?cantly increased in 750 mg/kg H. officinalis extract compared to the other treatments. There was no significant difference in the amounts of albumin, glucose, cortisol, cholesterol, triglyceride, creatinine, urea, aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), lipase, and amylase of all treatments (P>0.05). Total antioxidant capacity (TAC) significantly increased in the treatment containing H. officinalis extract. Serum malondialdehyde (MDA) decreased in the treatments supplemented with H. officinalis extract. The lowest MDA was observed in 750 mg/kg H. officinalis extract, which was significantly different from other treatments. Relative survival percentage (RSP) against A. hydrophila increased in the treatments fed with H. officinalis extract. The highest RSP was observed in 750 mg/kg H.  officinalis extract treatment. It can be concluded that dietary H. officinalis extract had a proper effect on immune system stimulation, antioxidant capacity, and resistance against A. hydrophila in the studied fish.