Minaz, Mert; Félix, Luís M.; Er, Akif; Köse, Özay; Ak, Kübra; Alparslan, Cem; Serdar, Osman; Aydın, Baki; Kurtul, Irmak; Hoseini, Seyyed Morteza

Anesthesia practices in aquaculture are important for preventing potential stress in fish. For this purpose, interest in natural anesthetic agents as substitute for currently used synthetic anesthetics has increased. In this context, the present study demonstrated the anesthetic efficacy of citronella oil (Cymbopogon nardus) in rainbow trout (Oncorhynchus mykiss) individuals. Based on an artificial neural network (ANN) model derived from preliminary studies, the optimal anesthetic concentration for rainbow trout individuals was estimated as 90 μL L−1. Validation of the concentration predicted by ANN revealed no time-dependent hematological or histological effects on fish to citronella oil. Furthermore, biochemical tests revealed that the partial post-anesthesia increase in ALT and AST values was transient and negligible in light of histological findings. Although oxidative stress was observed during the acute period, the enzymatic activity of SOD and CAT effectively reduced the oxidative damage, demonstrating their role in protecting the fish from oxidative stress. The antioxidant activity observed was temporary, returning to baseline levels without any accompanying tissue damage at the tested concentration. Behavioral monitoring further indicated a swift reduction in motor activity followed by a smooth recovery process, with no evident signs of stress or avoidance behaviour. Overall, these results position citronella oil as a promising natural anesthetic for rainbow trout under the studied parameters. That said, further studies involving various solvents, temperature ranges, and fish species are necessary to comprehensively establish its efficacy and safety.

AtıfScopus4

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Minaz, Mert; Er, Akif; Ak, Kübra; Serdar, Osman

In aquaculture, interest in natural anesthetic agents as alternatives to synthetic anesthetics has been steadily increasing. This is due to concerns over residue accumulation, environmental impact, and growing demand for sustainable practices. Within this context, the present study focused on the anesthetic effects of nutmeg essential oil at three different concentrations in rainbow trout (Oncorhynchus mykiss, 94.42 ± 23.9 g): low (400 µL/L), medium (600 µL/L), and high (800 µL/L). Induction and recovery times were recorded, and samples were collected at 0, 2, 4, and 8 hours post-anesthesia for antioxidant, cortisol, and hematological analyses. Additionally, gill tissues were sampled immediately after anesthesia for histological examination. While the induction time for the low concentration exceeded 3 minutes, the induction and recovery times for the other concentrations ranged within acceptable limits (3 min for induction and 5 min for recovery). Blood parameters exhibited an increasing trend until the 4th hour post-anesthesia, peaking at the 2nd hour, before returning to control levels by the 4th hour. Histological evaluation revealed healthy gill tissues in the control and low-concentration group (400 µL/L), whereas hyperplasia was observed in the medium (600 µL/L) and high-concentration (800 µL/L) groups. Antioxidant enzyme activity (superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA), and glutathione peroxidase (GSH-Px)) indicated potential oxidative stress at the high anesthetic concentration. Similarly, cortisol levels were higher at the high concentration, with plasma cortisol showing a slight initial increase followed by a return to normal levels over time. In conclusion, this study highlights that nutmeg oil at a concentration of 600 µL/L may serve as a promising natural alternative to synthetic anesthetics in aquaculture. However, future studies should include a synthetic anesthetic as a control to allow for direct comparisons and a more comprehensive evaluation of its efficacy and physiological effects.

AtıfScopus8·WoS7·OpenAlex7

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