Pollutants impact fish health, leading to environmental diseases. Anionic surfactant detergents and
MPs (MPs) consist serious threat in freshwater environments either lonely or in combination. However,
their combined effects are not well studied. Our research therefore focuses on studying the harmful
effects of the anionic surfactant sodium lauryl sulfate (SLS) and polyethylene MPs (PMPs) on the
biology of freshwater African catfish (Clarias gariepinus), either alone or in combination. A 15-day
exposure trial to PMPs (10 mg/L), SLS (4 mg/L), or their combination was conducted. Hematological,
biochemical, antioxidant, and immunological markers were estimated. The erythrocytic morphology
was investigated. The pathological harms were monitored, and the histological abnormalities were
scored. In addition, histochemical appraisals of fibrosis and hypoglycemia in the liver and spleen
were estimated. This was achieved by semi-quantification of polysaccharide deposits and the fibrotic
collagen density and distribution pattern in the tissue micro-sections. On the one hand, our findings
revealed deteriorated biological markers in C. gariepinus exposed to PMPs (10 mg/L) or SLS (4 mg/L)
by close levels. Significant decreases in the hematological indices, while substantial increases in
the biochemical markers were recorded. As well, significant decreases were recorded in the total
antioxidant capacity and superoxide dismutase, while an elevation was recorded in the level of IL-1β
and IL-6 cytokines. Poikilocytosis of erythrocytes and severe hepatic and splenic pathological lesions
were observed. Furthermore, high levels of fibrosis and hypoglycemia were detected. On the other
hand, our findings showed antagonistic effects upon the combined exposure to PMPs (10 mg/L) and
SLS (4 mg/L). Fluctuated non-significant differences were observed in hematology and biochemical
markers. Mild erythrocytic poikilocytosis and moderate pathological lesions were scored in liver as well
as spleen. In addition, moderate quantitative fibrosis, and hypoglycemia were estimated. Exposure to
PMPs and SLS deteriorate the biology and pathology of C. gariepinus by severe effects. Interestingly,
ameliorated biological alterations were recorded evidenced a surprising antagonistic effect of
PMPs + SLS. Possibly, a chemical chelation between both reagents counteracted their singular effect
inside the biological system, which retorted their harm. Therefore, further investigations by chemists
on the probable chemical interaction between PMPs and SLS inside biological systems, which might
change their physical or chemical characteristics, may explain the case.