The current study was a pioneer attempt to explore the toxicological impacts of imidacloprid (IMI) pesticide and to investigate the efficiency of Hyphaene thebaica fruit (HTF) as a dietary supplement in attenuating the IMI effect in African catfish (Clarias gariepinus). Fish were sampled after 2 months of exposure to IMI (1/5 LC50: nominal 2.03 μg/L) and HTF (15 g/kg diet) supplementation, in combination or individually. Growth, hematological, stress, and antioxidant indicators, besides the mRNA expression of various genes in gills tissues and immunohistochemical and economic parameters, were assessed. The outcomes demonstrated that IMI exposure induced behavioral changes, and a significant decrease (p < 0.05) in the majority of the measured variables including growth, hematology, economic efficiency, neurotransmitter (acetylcholine esterase), glucose level, and antioxidant capacity (catalase, and superoxide dismutase (SOD)). Additionally, IMI dysregulated the expression of tumor necrosis factor-alpha (TNF-α), Toll-like receptor 5 (TLR-5), Toll-like receptor 1 (TLR-1), lysozyme C (LYSC), lysozyme G (LYSG), transforming growth factor-beta (TGF-β), myeloperoxidase (MYE), CXC chemokine (CXC), heat shock proteins 90 (HSP90), and SOD1 in the gills. On the other hand, marked increases in the serum malondialdehyde and stress indicator (cortisol) with the highest mortality losses were detected in IMI-exposed fish. Histopathological disorders are detected in the brain post-exposure to IMI including marked neuronal vacuolation, neuronophagia, and complete neuronal loss with weak BCL-2 and marked caspase-3 immunoreactivity. The dietary intervention with HTF revealed a noticeable modulation in the aforementioned parameters and regeneration in the histological architecture. Taken together, the IMI induces severe stress, and behavioral and histological alterations, and impairs the C. gariepinus growth, economic efficiency, and hematological, and antioxidant efficacy through the negative transcriptional impact on the associated genes. Nevertheless, the dietary HTF (15 g/kg diet) could be utilized as a potential natural growth promoter, antioxidant modulator, and against IMI hazards for sustaining aquaculture.