The protective effects of dietary microalgae against hematological, biochemical, and histopathological alterations in pyrogallol-intoxicated Clarias gariepinus

Microalgae have well-established health benefits for farmed fish. Thus, this study aims to explore the potential protective effects of <i>Spirulina platensis</i>, <i>Chlorella vulgar</i>is, and <i>Moringa oleifera</i> against pyrogallol-induced hematological, hepatic, and renal biomarkers in African catfish (<i>Clarias gariepinus</i>), as well as the histopathological changes in the liver and kidney. Fish weighing 200 ± 25 g were divided into several groups: group 1 served as the control, group 2 was exposed to 10 mg/L of pyrogallol, and groups 3, 4, and 5 were exposed to the same concentration of pyrogallol, supplemented with <i>S. platensis</i> at 20 g/kg diet, <i>C. vulgar</i>is at 50 g/kg diet, and <i>M. oleifera</i> at 5 g/kg diet, respectively, for 15 days. Exposure to pyrogallol led to decreased packed cell volume (PCV) and lymphocyte count, but these effects were alleviated by microalgae interventions. <i>C. vulgar</i>is and <i>M. oleifera</i> equally restored PCV and increased lymphocyte counts. Supplementation with <i>C. vulgar</i>is and <i>M. oleifera</i> successfully normalized both neutrophil and eosinophil counts. Pyrogallol intoxication engenders an increase in glycemic status, but <i>C. vulgar</i>is and <i>M. oleifera</i> effectively mitigated this rise. Pyrogallol-exposed fish exhibited signs of renal dysfunction, with increased serum creatinine and total cholesterol levels. A significant decrease in both erythrocytic cellular and nuclear abnormalities was observed following supplementation with microalgae. <i>C. vulgaris</i> and <i>M. oleifera</i> showed promise in decreasing serum glucose and creatinine levels, and improving hematological parameters, while <i>S. platensis</i> exhibited limited efficacy in this regard. Exposure to pyrogallol led to a notable decrease in serum superoxide dismutase activity and total antioxidant capacity (TAC), accompanied by an increase in serum malondialdehyde (MDA) levels. Diets enriched with <i>C. vulgaris</i> and <i>M. oleifera</i> effectively restored these parameters to normal levels, whereas <i>S. platensis</i> did not induce significant changes. None of the microalgae improved TAC except for <i>M. oleifera</i>, which significantly enhanced it. MDA levels returned to control levels equally and significantly across all groups. Interleukin-6 levels did not exhibit significant differences between any of the groups. Collectively, the histopathological changes induced by pyrogallol were most prominently alleviated in the pyrogallol + <i>C. vulgar</i>is and pyrogallol + <i>M. oleifera</i> groups, and to a limited degree in the pyrogallol + <i>S. platensis</i> group. While the tested microalgae did not cause hepatic or renal dysfunction, they did lead to metabolic abnormalities. The incorporation of microalgae into the diet holds significant importance in mitigating the metabolic and histological toxicity of pyrogallol and should be considered in the formulation of fish feed.