Abstract

Background:
Adding oregano essential oil (OEO) as a supplement has great potential to improve fish production efficiency.

Aim:
Current research was executed to assess the prospective impact of OEO incorporation into tilapia diets on physiological response, growth performance, oxidative capacity, and immune status when subjected to Aeromonas hydrophila infection.

Methods:
Three different experimental diets were prepared by augmenting a 30% protein basal diet with OEO at concentrations of 0, 0.5, and 1 g/kg feed. Each of the three treatment groups consisted of sixty fish (three copies of twenty fish each) and was randomly assigned out of 180 healthy Nile tilapia (O. niloticus) fingerlings. For 8 weeks, fish in nine separate glass tanks were given individualized diets containing 3% biomass. The survival rate (SR%) of the fish was measured after 15 days of observation following intraperitoneal injection of pathogenic A. hydrophila.

Results:
Physiological performance, antioxidant indicators, immunological function (phagocytic activity, lysozyme, and phagocytic index), and growth metrics were all enhanced in fish that were given OEO supplements. Antibiotics may be a new contender: oregano oil, when consumed orally, reduces pathogenic oxidative stress. The villus height, breadth, and depth were enhanced by oregano oil, which also improved intestinal morphology. On the other hand, animals infected with A. hydrophila exhibited signs of deterioration in the spleen, hepatopancreas, and intestinal tissues.

Conclusion:
For optimal development, immunity, performance in physiological tests, and gut health, Nile tilapia fingerlings are fed half a gram per kilogram of OEO.

Key words: Keywords: Aeromonas hydrophila, Nile tilapia, Oregano essential oil, Oxidative status