Inclusion of Oregano vulgare extract as supplement in Catla catla: Impacts on growth, hematology and biochemical parameters

As an alternative to synthetic chemicals, natural herbs can greatly improve fish's health and growth potential. This investigation aimed to explore the possibilities of oregano ( Oregano vulgare L.) extract as a phytogenic feed additive in improving the growth, blood profile, carcass composition, whole-body mineralization, serum biochemistry and antioxidant activity of Catla catla (average initial weight = 9.26±0.03 g/fish). Triplicate groups of fish were fed diets having various percentages of oregano extract (0 %, 0.5 %, 1 %, 1.5 %, 2 %, 2.5 % and 3 % per kg diet) twice daily for 90 days. The findings found that parameters of growth such as weight gain, weight gain%, feed conversion ratio, survival rate, protein efficiency ratio, and specific growth rate increased substantially ( p <0.05), in fish fed diets with 1 %-1.5 % oregano extract supplementation relative to the other treatments. Carcass composition and hematological parameters were improved significantly ( p <0.05) as oregano extract concentrations increased from 1 % to 1.5 % per kg compared to control and other groups. Results also indicated that minerals in the body of fish improved significantly ( p <0.05) when extract concentrations increased from 1 %--1.5 % in the diet. Furthermore, immune parameters and hepatic enzymes activities in fish improved considerably ( p <0.05) at these concentrations, indicating optimal antioxidant protection and disease resistance. In contrast, all fish parameters were decreased notably ( p <0.05) in control and groups based on 2.5 % and 3 % oregano extract. In conclusion, the supplementation of 1 %-1.5 % oregano extract in the diets of C. catla could significantly ( p <0.05) improve the overall performance of fish. • The medicinal herb, Oregano vulgare , offers a potentially cost-effective and sustainable alternative for fish feed. • Oregano extract enhances growth, health, and nutritional quality of Catla catla . • Adding 1 %-1.5 % oregano extract to C. catla fingerlings' diets boosts their immunity, growth, and overall health.