Post-harvest pesticide application during storage of cured fish has been reported in Nigeria, raising concerns for consumer health and compliance with international trade standards. The study analysed organochlorine and organophosphate pesticide residues in freshly cured and long-term stored (“distant landed”) Clarias spp., Gymnarchus spp., and Heterotis spp. Purchased from Ose Market, Onitsha, Nigeria. Edible muscle samples were extracted, cleaned using gel permeation chromatography, and quantified by gas chromatography–mass spectrometry (GC–MS). Method validation included matrix-matched calibration (R2 ? 0.997), recoveries (75–98%), and limits of detection of 0.2–1.2 ng/g. Distant landed cured fish contained significantly higher residue levels than freshly cured fish (p < 0.05). The highest organochlorine concentrations were endosulfan (17.779 µg/g) in Heterotis spp. and 2,4-dichloroethane (12.595 µg/g) in Heterotis spp. The highest organophosphate concentration was chlorpyrifos (22.148 µg/g) in Gymnarchus spp. Freshly cured fish contained lower levels, with most compounds undetected except 2,2-dichlorovinyldimethylphosphate in Heterotis spp. All detected residues exceeded Codex Alimentarius and EU maximum residue limits by several orders of magnitude. The findings indicate that pesticide contamination in cured fish in Nigerian markets is primarily due to post-harvest handling and storage practices. Such contamination poses serious dietary risks and threatens market access for Nigerian fish products. Regulatory enforcement, capacity building for fish processors, and promotion of safer preservation methods are urgently required to protect public health and sustain fisheries trade.
Preserved fish, Residual agrochemical, GCr–MS, food quality, Sub-saharan Africa