Chitosan-Vitamin C Nanoparticles Ameliorate Heat Stress in the Nile Tilapia | ||||
| Egyptian Journal of Aquatic Biology and Fisheries | ||||
| Article 119, Volume 29, Issue 4, July and August 2025, Page 2169-2193 PDF (1.05 MB) | ||||
| DOI: 10.21608/ejabf.2025.445719 | ||||
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| Author | ||||
| Fadel et al. | ||||
| Abstract | ||||
| Climate change has become a global concern, with rising temperature extremities affecting the survival of aquatic animals. In this study, the Nile tilapia (Oreochromis niloticus) were divided into seven groups and fed diets for eight weeks: a control group with no feed additives, a group supplemented with bulk vitamin C (420 mg/kg dry diet), and five groups receiving vitamin C nanoparticles (VCNPs) at 20, 40, 60, 80, and 100% of the recommended dose—equivalent to 84, 168, 252, 336, and 420mg/ kg dry diet, respectively. The immune-oxidative status and resistance to Aeromonas hydrophila were evaluated following exposure to a low water temperature of 18 ± 0.5°C. All fish fed VCNP-supplemented diets showed significantly improved growth performance and reduced feed conversion ratios (FCR, ranging from 2.25 to 1.89), compared to those fed bulk vitamin C (FCR = 2.43) and the control group (FCR = 2.6). Serum cortisol levels increased significantly after 6 hours of heat stress, and serum glucose rose after 24 hours in all groups. However, VCNP-fed groups showed a significantly faster return to basal levels (0 h). The expression of the SOD gene was the highest in the VCNPs100 and VCNPs80 groups, with fold-changes of 6.8 and 6.5, respectively. No significant changes were observed in CAT gene expression 24 hours post-stress. Tilapia fed VCNP diets exhibited lower mortality rates following A. hydrophila infection, with relative protection levels of 33.3% (VCNPs100), 16.67% (VCNPs80), and 16.67% (VCNPs60). Regardless of bacterial infection, expression levels of TNF-β and IL-1β in the head kidney were lower in VCNP groups compared to the bulk VC and control groups. These pro-inflammatory markers significantly increased in response to A. hydrophila challenge. Interestingly, the bacterial infection did not influence HSP70 gene expression. Under heat stress, control fish exhibited signs of stress, including greenish-discolored livers, normal-sized spleens, empty intestines, and pale gills. In contrast, VCNP-fed groups maintained normal body coloration and organ appearance. In conclusion, dietary supplementation with VCNPs enhances the Nile tilapia’s ability to tolerate low water temperatures and improves resistance to Aeromonas hydrophila infection. | ||||
| Keywords | ||||
| Chitosan; Vitamin C; Antioxidants; Cytokines; Heat stress; Oreochromis niloticus | ||||
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