Globally, the contamination of aquatic bodies by improper application of pesticides, particularly fungicides, endangered aquatic life and hampered sustainable aquaculture. Exploring innovative strategies to mitigate this difficult issue as eco-friendly and cost-effective is indispensable. Herein, the potential of dietary Egyptian mallow (Malva parviflora) leaves (EML) as a powder form to mitigate the toxicological implications of metiram (MET) exposure in Oreochromis niloticus (Nile tilapia) was assessed in this attempt. The investigation featured growth, physiological, immune/antioxidant responses, splenic cytokines expression, and histopathological concepts. In light of this, fish (N = 200; 32.80 ± 0.92 g) were eventually assigned into four groups with five sets (control, EML, MET, and EML + MET) for 63 days. The control and EML groups were given basal diets that had 0 and 15 g EML/kg diet, respectively, without MET exposure. Furthermore, MET and EML + MET groups were received the identical diets as control and EML groups, respectively, and exposed to 0.38 mg/L MET. The findings highlighted a significant (P < 0.001) growth retardation (declining in weight gain and specific growth rate) and higher fish mortality (32%) by MET exposure. Also, immune impairment (lowered immunoglobulin M and complement 3) and oxidative damage (higher malondialdehyde and declined catalase and superoxide dismutase) were the outcomes of MET toxicity. In addition, the biochemical biomarkers showed substantial disruptions (P < 0.001) in the MET group, where creatinine, aspartate aminotransferase, and alanine aminotransferase increased. Splenic expression of immune-relevant cytokines (interleukin-10 and interferon-gamma 1) was downregulated with upregulation of apoptosis (cysteine-aspartic acid protease-3) linked gene by MET toxicity (P < 0.001). Histologically, MET significantly provoked a diverse range of aberrations in the spleen, kidney, and liver tissues. Remarkably, feeding the EML diet to the MET group decreased fish mortality (14%) and refined all metrics, while retaining the histological integrity of tissues. The conclusion of this viewpoint recommends using dietary EML (15 g/kg) to diminish the deleterious effects of MET in toxicity in Nile tilapia to sustain aquaculture.