Microbial Contamination and Insect Pest Infestation of Traditionally Smoked Fish Sold in Selected Markets in Makurdi, Nigeria: Implications for Post-harvest Quality and Food Safety

Abstract

This study investigated microbial contamination and insect pest infestation in smoked fish sourced from Wurukum and Wadata, two major retail fish markets in Makurdi, the capital of Benue State. Smoked fish remains an accessible source of animal protein in Nigerian markets; however, species-level characterisation of simultaneous microbial contamination and insect infestation during open-market storage remains a critical post-harvest knowledge gap. Three commercially important species (Protopterus annectens, Oreochromis niloticus, and Clarias gariepinus) were purchased and sealed in polyethylene bags for transport to the laboratory. Total viable count (TVC), total coliform count (TCC), and total fungal count (TFC) were assessed using standard pour-plate methods, and isolates were identified through Gram staining, biochemical tests, and morphological characterisation. Protopterus annectens from Wurukum recorded the highest TVC (2.06 × 10² ± 2.00 cfu/g) and TCC (75.00 ± 1.00 cfu/g), whereas Oreochromis niloticus from Wadata yielded the highest TFC (70.50 ± 2.50 cfu/g). Clarias gariepinus showed the lowest TCC values in both markets. Klebsiella spp., Proteus spp., and Bacillus spp. were detected in all fish-market combinations; Mucor, Rhizopus, and Fusarium were confined to Clarias gariepinus; and Streptococcus spp. occurred only in Protopterus annectens. Dermestes maculatus was the predominant insect pest, with the highest mean infestation recorded in Protopterus annectens from Wadata (17.13 ± 6.86). Significant differences (P < 0.05) across all parameters indicate the need for improved smoking practices, hygienic storage, and integrated post-harvest pest management.