<p>Microplastic (MP) pollution has emerged as a pervasive threat to freshwater ecosystems worldwide, with increasing evidence of contamination in freshwater fish that serve critical ecological, economic, and nutritional roles. This review synthesizes current knowledge on the sources, pathways, detection methodologies, occurrence, tissue distribution, ecotoxicological effects, and human health implications of microplastics in freshwater fish. Major sources of MPs include urban wastewater, industrial effluents, agricultural runoff, aquaculture activities, and atmospheric deposition, which facilitate their entry into rivers, lakes, reservoirs, and wetlands. Advances in analytical techniques such as Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and pyrolysis–gas chromatography/mass spectrometry have improved MP detection; however, methodological inconsistencies continue to hinder data comparability. Globally, freshwater fish frequently ingest MPs, with fibers and fragments being the dominant morphotypes and polyethylene, polypropylene, polyethylene terephthalate, and polyamide the most common polymers. Beyond the gastrointestinal tract, MPs have been detected in gills, liver, muscle, gonads, and eggs, indicating potential translocation and reproductive transfer. Exposure to MPs can induce oxidative stress, tissue damage, metabolic disturbances, and reproductive impairment in fish. Furthermore, consumption of contaminated fish may expose humans to MPs and associated pollutants, raising concerns regarding food safety and public health. The review identifies key research gaps and highlights the need for standardized methodologies, long-term monitoring, risk assessment frameworks, and integrated mitigation strategies to protect freshwater biodiversity, fisheries, and food security.</p>