COMPARATIVE STUDY OF PARASITIC INFECTIONS, WATER QUALITY, AND PATHOLOGICAL EFFECTS IN CULTURED AND WILD FISH POPULATIONS IN JOS METROPOLIS, NIGERIA

Abstract

Fish serve as a vital, affordable source of animal protein in Nigeria, but parasitic infections and environmental degradation threaten the sustainability of aquaculture. This study evaluated parasitic infections, water quality, and organ histopathology in wild (n = 174; catfish and tilapia) and cultured (n = 150; catfish) fish across Jos Metropolis, Plateau State, during the 2025 rainy season (May–October). Physicochemical water parameters generally met standard aquaculture guidelines across all sites. However, cultured environments showed higher nutrient enrichment, featuring elevated turbidity (10.5-12.6 NTU), conductivity (181-190 μS/cm), nitrate (6.2–7.5 mg/L), and phosphate (0.54-0.61 mg/L). Overall prevalence rates for haemoparasites and intestinal parasites were 24.1 % (78/324) and 15.7 % (51/324), respectively. Haemoparasite (Haemogregarina spp.) prevalence was significantly higher in wild fish, peaking at 87.5 % in Oreochromis niloticus from Kara Dam, compared to 0.0-30.0 % in cultured catfish. In contrast, intestinal parasite rates were similar between wild (15.5 %) and cultured fish (16.0 %), with Entamoeba spp. identified as the predominant taxon. Histopathological evaluation demonstrated more severe hepatic and renal lesions—primarily congestion and focal necrosis—in wild fish, aligning with their elevated haemoparasite burden. Cultured fish displayed milder pathological alterations despite facing higher nutrient loads, while gastric tissues showed no significant damage across groups. Overall, these findings demonstrate that wild fish face greater parasite-induced pathology, whereas cultured systems show elevated nutrient levels. Implementing routine parasitological monitoring, proactive aquaculture management, and improved environmental sanitation is essential to safeguard fish health, ensure food security, and protect public safety in the region.