Occurrence and Characterisation of Microplastics in Fish Tissues and Water from Yusuf Bage River, Unguwar Rimi, Kaduna State, Nigeria

Microplastic pollution in freshwater systems is a growing environmental concern with potential implications for aquatic organisms and human consumers through the food chain. This study assessed the occurrence and characteristics of microplastics (MPs) in fish tissues and water samples collected from Yusuf Bage River, near Unguwar Rimi, Kaduna State, Nigeria. A total of 18 fish specimens (n = 6 per species) comprising African catfish (Clarias gariepinus), Nile tilapia (Oreochromis niloticus) and silver moony (Monodactylus sebae), together with six water samples, were collected in May 2025. Fish tissues (flesh, gills and intestine) and water samples were subjected to potassium hydroxide (KOH) digestion, density separation, stereomicroscopic enumeration, Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy and Scanning Electron Microscopy (SEM). FTIR spectra indicated dominant polyethylene (PE) signatures (CH₂ rocking at 720–730 cm⁻¹), with contributions from polyethylene terephthalate (PET) and polypropylene (PP), confirmed by library match quality factors ≥ 0.75. SEM revealed irregular fragments, fibres and sheet-like particles with sharp edges and weathering features. Microplastics were present in all tissues and water, with mean abundances ranging from 2.3 ± 0.8 to 8.7 ± 2.1 particles/g wet weight in fish tissues and 45.3 ± 12.6 particles/L in water. Higher abundances were observed in gills (5.8–8.7 particles/g) and intestine (4.2–7.1 particles/g) compared with flesh (2.3–3.8 particles/g). Findings document measurable microplastic contamination in this urban-influenced river and provide a baseline for future monitoring and management.