Physiological and histological investigations of gills in juvenile Oreochromis niloticus transported with essential oil Lippia origanoides
摘要
The transport of fish is a critical stage in aquaculture, as it may cause stress and compromise animal health. The use of phytotherapeutics, such as essential oils, has been investigated as an alternative to mitigate the negative impacts of this management practice. This study evaluated the effect of essential oil Lippia origanoides (EOLO) in the transport water of Nile tilapia (Oreochromis niloticus) juveniles. Four EOLO concentrations (5, 10, 15, and 20 mg L⁻1) and a control were tested in a completely randomized design with four replicates during a 5-h transport period. Water quality parameters, survival, hematological and biochemical indices, and gill histopathological changes were analyzed. Transport increased dissolved oxygen, electrical conductivity, and total ammonia levels, but values remained within non-toxic limits for the species. Survival was 100% at the end of transport, with no significant differences during recovery. No relevant changes were observed in hematological or biochemical parameters, except for an isolated increase in AST in the 10 mg L⁻1 group. Gill histological changes were classified as mild and attributed to transport itself, only the concentration of 20 mg L−1 of EOLO differed from the control group. It can be concluded that EOLO, at concentrations up to 20 mg L⁻1, can be safely used in the transport water of Nile tilapia juveniles, representing a natural and potentially sustainable approach to decreasing reliance on synthetic anesthetics in aquaculture.