Abstract
Fungal infections represent a major constraint in intensive aquaculture systems, particularly under suboptimal environmental conditions. Striped catfish (Pangasianodon hypophthalmus) is an economically important species widely cultured in Egypt; however, limited information is available regarding fungal disease resilience and the potential use of organic acids as protective agents. This study investigated the prevalence of fungal infection in cultured striped catfish, evaluated associated water quality parameters, and assessed the protective efficacy of dietary organic acids.
Clinically diseased fish exhibited external lesions, skin discoloration, and cotton-like growths. Fungal isolates were identified phenotypically and confirmed molecularly by PCR amplification of a specific fragment producing a 200 bp amplicon. Water quality analysis revealed reduced dissolved oxygen and elevated ammonia levels, which likely contributed to increased susceptibility to infection.
An experimental challenge trial was conducted to evaluate the protective role of organic acids. Fish were divided into control and treated groups, and clinical signs, mortality rates, and behavioral responses were recorded. Results demonstrated that fish receiving organic acid supplementation showed improved survival rates, reduced lesion severity, and enhanced general health status compared to untreated controls. Histopathological findings further supported the protective effects of organic acids in maintaining tissue integrity.
Statistical analysis indicated significant differences (P < 0.05) between treated and control groups in terms of mortality and clinical progression. The findings suggest that environmental stressors, particularly poor water quality, play a critical role in fungal outbreaks, while dietary organic acids may serve as an effective supportive strategy to enhance disease resilience in striped catfish.
In conclusion, the integration of proper water quality management and dietary organic acid supplementation could provide a sustainable approach to reducing fungal disease impact in Egyptian aquaculture systems.
systems.

Key words: Aspergillus flavus, Candida albicans, butyric acid, formic acid, and striped catfish