International Journal of Aquaculture, 2026, Vol.16, No.2, 74-89 http://www.aquapublisher.com/index.php/ija 82 This is a qualitative comparative assessment; no statistical analysis was applied. The results indicate a trade-off between potency and safety, with C. limon being highly effective but less safe. Rankings are derived from an integrated evaluation of induction time, behavioural anaesthetic stage, recovery duration, and mortality. Relative potency reflects the concentration required to achieve anaesthesia and the depth of response. Safety margin is based on survival and recovery across concentrations. Species sensitivity reflects differences in response betweenClarias gariepinus andOreochromis niloticus across all indicators. 3.6 Water quality conditions during the experiment Water quality parameters remained within recommended ranges throughout the experimental period (Table 7). Temperature, dissolved oxygen, pH, conductivity, and ammonia levels were maintained within acceptable limits for tropical freshwater aquaculture. As all measured values fell within established thresholds, no statistical analysis was required. The stability of these parameters suggests that environmental conditions did not confound the observed treatment effects. Table 7 Water quality parameters Parameter Observed Range Recommended Range Status Temperature (°C) 26.4–27.3 24–30 Suitable Dissolved oxygen 5.8–6.3 ≥5.0 Adequate pH 6.8–7.3 6.5–8.0 Stable Conductivity 182–191 150–400 Acceptable Ammonia 0.01–0.02 <0.05 Safe All values fall within recommended aquaculture limits; no statistical comparison required. Environmental conditions were within recommended ranges and are unlikely to have confounded experimental outcomes 3.7 Effects of extracts on flesh quality parameters Flesh quality parameters are presented (Table 8). Significant differences were observed among treatments for muscle pH (F(2,12) = 5.84, p = 0.017), crude protein content (F(2,12) = 4.96, p = 0.027), and lipid content (F(2,12) = 6.21, p = 0.014). Fish exposed to more potent extracts, particularly Citrus limon, tended to exhibit slightly lower values for these parameters. Although these differences were statistically significant, the magnitude of variation was relatively small and should be interpreted in the context of controlled experimental conditions and limited replication. Table 8 Flesh quality parameters following exposure Treatment Species pH (mean ± SE) Protein Lipid Sweet Orange O. niloticus 6.8±0.07ᵃ 18.5 ± 0.21ᵃ 5.2±0.14ᵃ Sweet Orange C. gariepinus 6.9±0.08ᵃ 17.9 ± 0.16ᵃ 5.4±0.13ᵃ Sour Orange O. niloticus 6.7±0.09ᵇ 18.1 ± 0.19ᵃ 5.0±0.11ᵇ Sour Orange C. gariepinus 6.6±0.08ᵇ 17.5 ± 0.15ᵇ 5.1±0.12ᵇ Lemon O. niloticus 6.5±0.07ᶜ 17.0 ± 0.18ᶜ 4.8±0.13ᶜ Lemon C. gariepinus 6.4±0.08ᶜ 16.8 ± 0.14ᶜ 4.7±0.12ᶜ Values are mean ± SE (n = 3). Different superscripts indicate significant differences at p < 0.05 (ANOVA, Tukey’s HSD). Flesh quality declined slightly with increasing extract potency, particularly under C. limon treatment. 3.8 Post-exposure welfare and behavioural recovery Post exposure behavioural recovery is summarised in Table 10. Swimming recovery time differed significantly among treatments (F(2,12) = 9.12, p = 0.004). Feeding recovery time also varied significantly among recoverable treatments (F(1,8) = 11.34, p = 0.010).
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