This study provides the first evidence that dietary Halimeda opuntia (HA) powder can mitigate chronic fluoride-induced toxicity in Nile tilapia (Oreochromis niloticus). Two hundred and fifty fingerlings (average initial weight: 11.60 ± 0.21 g) were randomly allocated into five experimental groups, each comprising five replicates of 10 fish, and maintained for 56 days. Treatments included a negative control (F−; fluoride-free water), a positive control (F+; fluoride-contaminated water with 6.1 mg L-1, equivalent to 1/10 of the 96-h LC50 of sodium fluoride), and fluoride-stressed groups supplemented with 2.5, 5, or 10 g kg-1 HA (F+ + HA2.5, F+ + HA5, F+ + HA10). Fluoride exposure alone (F+) significantly impaired all growth indices (p < 0.001) and feed utilization (FCR; p < 0.001), disrupted biochemical indices (declined AST, P < 0.001, elevated both UA and triglycerides, P < 0.01), suppressed antioxidant (SOD, P < 0.05, GSH, P < 0.01) and innate immune activities (lysozyme, P < 0.05), and sharply increased TNF-α and MDA (P < 0.001) values. Severe histopathological lesions were also observed in the intestine and hepatopancreas. Conversely, dietary H. opuntia mitigated these disturbances in a dose-dependent manner. Specifically, at 2.5 and 5 g kg−1, growth and feed efficiency improved (P < 0.05–0.001), along with partial restoration of antioxidant and immune parameters. The most pronounced protection was observed at 10 g kg−1, where FBW and FCR were nearest to F− values (P < 0.001 vs. F+), while UA (P < 0.01), triglycerides (P < 0.05), TNF-α (P < 0.001), and MDA (P < 0.001) declined significantly. Histology examination revealed nearly normal intestinal and hepatopancreatic architecture at HA10 compared with positive control group. Meanwhile, gene expression analysis confirmed that HA10 upregulated PCNA (P < 0.001), SOD (P < 0.0001), and GPx (P < 0.001) while downregulating Caspase-3 (P < 0.0001). In conclusion, H. opuntia, particularly at 10 g kg−1 could effectively mitigate the deleterious consequences of fluoride toxicity on growth, biochemical balance, immunity, and cellular defensive mechanisms in Nile tilapia, supporting its application as a functional and protective feed additive in aquaculture.

Protective role of Halimeda opuntia supplementation in mitigating waterborne fluoride toxicity in Nile tilapia: Insights into growth, antioxidant, immune, and molecular responses

期刊论文
发表日期：

2026年1月8日

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Mohammed A. E. Naiel,
Eman M. Zaki,
Doaa K. Khames,
Nahla E. M. Ismael,
Xiaolin Meng,
Hanan M. Alharbi,
Khairiah Mubarak Alwutayd,
Doaa M. R. Anees

摘要

This study provides the first evidence that dietary Halimeda opuntia (HA) powder can mitigate chronic fluoride-induced toxicity in Nile tilapia (Oreochromis niloticus). Two hundred and fifty fingerlings (average initial weight: 11.60 ± 0.21 g) were randomly allocated into five experimental groups, each comprising five replicates of 10 fish, and maintained for 56 days. Treatments included a negative control (F⁻; fluoride-free water), a positive control (F⁺; fluoride-contaminated water with 6.1 mg L^-1, equivalent to 1/10 of the 96-h LC₅₀ of sodium fluoride), and fluoride-stressed groups supplemented with 2.5, 5, or 10 g kg^-1 HA (F⁺ + HA_2.5, F⁺ + HA₅, F⁺ + HA₁₀). Fluoride exposure alone (F⁺) significantly impaired all growth indices (p < 0.001) and feed utilization (FCR; p < 0.001), disrupted biochemical indices (declined AST, P < 0.001, elevated both UA and triglycerides, P < 0.01), suppressed antioxidant (SOD, P < 0.05, GSH, P < 0.01) and innate immune activities (lysozyme, P < 0.05), and sharply increased TNF-α and MDA (P < 0.001) values. Severe histopathological lesions were also observed in the intestine and hepatopancreas. Conversely, dietary H. opuntia mitigated these disturbances in a dose-dependent manner. Specifically, at 2.5 and 5 g kg⁻¹, growth and feed efficiency improved (P < 0.05–0.001), along with partial restoration of antioxidant and immune parameters. The most pronounced protection was observed at 10 g kg⁻¹, where FBW and FCR were nearest to F⁻ values (P < 0.001 vs. F⁺), while UA (P < 0.01), triglycerides (P < 0.05), TNF-α (P < 0.001), and MDA (P < 0.001) declined significantly. Histology examination revealed nearly normal intestinal and hepatopancreatic architecture at HA10 compared with positive control group. Meanwhile, gene expression analysis confirmed that HA10 upregulated PCNA (P < 0.001), SOD (P < 0.0001), and GPx (P < 0.001) while downregulating Caspase-3 (P < 0.0001). In conclusion, H. opuntia, particularly at 10 g kg⁻¹ could effectively mitigate the deleterious consequences of fluoride toxicity on growth, biochemical balance, immunity, and cellular defensive mechanisms in Nile tilapia, supporting its application as a functional and protective feed additive in aquaculture.