A Dissertation 2019Fish is an important component of aquatic biodiversity in Tanzania and plays an important role in the national economy. However, the spatial-temporal distribution of fish in the Little Ruaha River Catchments and its contribution to household income have not been given sufficient evaluation. This study determined the spatiotemporal diversity and abundance of fish, generated the information spatial distribution of fish across the catchments and determine the contribution of fish to household income. Fish samples were collected during dry and rain season using gillnets of 76.2 mm mesh size in three sampling sites (in the upper reach, middle reach, and lower reach). Structured household questionnaire and field observation were used to collect information on the contribution of fisheries to household income. The Shannon diversity index was used to compute the diversity of fish in the different habitats and seasons. Kruskal-Wallis and Mann Whitney tests were used to determine the difference in fish diversity and abundance between habitats and seasons. The contribution of fisheries to household income was assessed as the mean proportion of household income obtained from fishing activities. A total of 250 fish individuals belonging to five species were captured. The fish species diversity and relative abundance was higher in the lower reach compared to the upper reach. The relative abundance of fish was statistically different (p<0.05) between habitat and seasons. However, there was no significant (p>0.05) difference in fish diversity between habitats and seasons. Oreochromis and Clarias were the common species across all habitats. Fisheries contributes to an individual monthly income of up to 500 000 TSA (US$ 220) and supplies about 51% of protein to community households. Sustainable fisheries management in river basins contributes significantly to community livelihoods. Management of river basins should integrate fisheries activities as among the options for integrated river basin management.