article · The Egyptian Journal of Aquatic Research
Stocking density and diet significantly influence the welfare and development of farmed fish. An investigation evaluated the combined effects of stocking densities and oregano essential oil dietary supplementation on juvenile Nile tilapia across a ten-week trial. Fish were reared at low, medium, and high densities and fed diets containing different concentrations of oregano essential oil. The essential oil improved fish growth performance under low and medium stocking densities. Tilapia displayed behavioural shifts across all densities, including reduced aggression in the high-density conditions. Furthermore, the essential oil reduced oxidative stress and aggressive behaviour in juvenile fish, as demonstrated by favourable shifts in cortisol levels and antioxidant enzymes. The supplement also functioned as a non-specific immune stimulant by increasing antioxidant and nitric oxide activity, helping to offset stress associated with rearing density.
Intensive aquaculture operations frequently face challenges related to crowding stress, which undermines fish welfare, immune health, and productivity. Demonstrating that natural plant extracts like oregano essential oil can curb aggression, lower oxidative stress, and stimulate immune responses provides fish farmers with potential dietary tools to maintain better welfare and growth without relying on synthetic chemicals.
This work points to the use of oregano essential oil as a natural functional feed additive for commercial aquafeed manufacturers and tilapia producers seeking to improve welfare and productivity under intensive rearing. Tested in small-scale aquarium trials over ten weeks, the application is at an early, laboratory-validated stage and will require testing in commercial production ponds or tanks to verify economic feasibility and optimal dosing at scale.
AI-generated from the published abstract. Always read the original work before citing.
To investigate the impacts of rearing density and oregano essential oil (OEO) supplementation on growth, behavioral and stress response of Nile tilapia, a factorial design (3 × 3 × 2) was assembled using 18 (100 L) glass aquaria where each aquarium had a rearing density and an OEO supplemental level. Six aquaria had a density of 10 fish aquarium−1 (low rearing density; LRD), another six had a density of 20 fish aquarium−1 (medium rearing density; MRD) and the remaining six aquaria had a density of 40 fish aquarium−1 (high rearing density; HRD). For each rearing density, fish were fed three diets with variable OEO levels (0.0, 1.0, and 2 ml kg−1 diet) and were assayed in two replicas for 10 weeks. OEO improved the growth performance of fish maintained at LRD and MRD. Tilapia exhibited behavioral changes in all densities with a reduced aggression in the HRD group. The OEO reduced the oxidative stress and the aggressiveness of juvenile tilapia as deduced from stress and welfare indicators’ levels (cortisol antioxidant enzymes). In addition, a density-stress related effect as well as a nonspecific immune stimulant effect of OEO was detected from the increased antioxidant and NO activity in this study.
This page summarises published work. The authoritative version sits with the publisher.
DOI: 10.1016/j.ejar.2018.06.008
Is something wrong with this record? Report it or request removal.
Discussion
Have you built on this work, tried to replicate it, or seen it applied in practice? Share what you know. Verified researchers and MARATTO™ domain experts can open a discussion, and any member can reply. Contributions are reviewed before they appear.
No discussion yet. Open the first thread.
New to MARATTO™? Create a free account.
