Freshwater crabs are a vital macro-invertebrate group in tropical inland waters worldwide, serving as indicators of good water quality and playing a significant role in nutrient cycling in tropical freshwater ecosystems. The West African freshwater crab, belonging to the family Potamonautidae, consists of over 88 species that are found in various streams and river systems across Africa. These crabs have adopted freshwater, semi-terrestrial, or terrestrial modes of life, and studying the population structure and biology of freshwater crabs is crucial for understanding their ecological and economic importance. Morphometric analysis is a powerful tool for population studies and provides valuable information on size relationships, distinguishing characters, and growth patterns, which are essential for further studies on species life history and resource management. Despite their ecological and economic importance, there is a dearth of information on the population structure and biology of freshwater crabs, including the Sudanonautes africanus, in the Lower River Benue, Makurdi, Benue State, Nigeria.