The decline of fish species in abundance is commonly attributed by factors such as general habitat degradation, modified patterns of stream flow, interrupted migratory pathways, reduced water quality and pollution, introduction of alien fish and diseases, illegal fishing and commercial overfishing and altered biotic interactions. From April 2023 to March 2024, spatial and temporal distribution of fishes in the Gilgel Abay River and its tributaries will be investigated. Study sites will be selected using purposive methods (based on the availability of natural and/or artificial barriers). As per the preliminary survey, six sampling points along the Gilgel Abay River, four sampling points on each (Ashar and Kelti) rivers and two sampling points on each (Jemma and Arib) rivers will be selected. This study is aimed at providing critical baseline information on the temporal and spatial patterns of fish communities in the Gilgel Abay River and its tributaries. Fish samples will be collected in the pre-rainy, rainy and post-rainy seasons of the year using a standard set of nets with different mesh sizes. The collected fish samples will be preserved in 5% formalin to be identified at the family and species level. The collected data will be analyzed using appropriate statistical methods and statistical software.