The spawning migration of Lake Tana 's Labeobarbus species to Arno-Garno River and its tributaries was studied from July to December 2010. Abiotic parameters such as dissolved oxygen, temperature, pH, total dissolved solids, conductivity and water transparency were measured from all sampling sites. Fish were sampled monthly in the non-peak spawning season (July, November and December) and twice in the peak spawning season (August to October) using 6,8, 10,12 cm stretched mesh size poly filament gill net. A total of 1077 Labeobarbus specimens were collected within the six sampling months (July to December 2010) from all sampling sites. Out of the total catch of Lab eo barb us the four dominant species contributed 93.03%. From the index of relative importance L. intermedius was the most important species. The monthly gonad-somatic indicated that the spawning season for Labeobarbus species was from August to October. Four species (L. intermedius, L.brevicephalus, L. nedgia and L. tsanensis) aggregated at the river mouth. Labeobarbus intermedius and L. tsanensis were the first species to aggregate in the river mouth starting from July and L. brevicephalus and L. nedgia had similar aggregation period in the river mouth starting from September. However, L. intermedius was the first to migrate to the upstream sites starting from the end of July followed by L. tsanensis at the second week of August. The last migrant was L. brevicephalus starting from the fourth week of August. Pair wise comparison of the Labeobarbus species showed temporal segregation in all sampling months, except these L. intermedius and L. brevicephalus that did not show temporal segregation with L. nedgia. To manage these migrating species, closing season should be strictly implemented at least at the peak spawning season from August to October. Keywords: Spatial and temporal segregation, Condition factor, Sex ratio, Closed season, Reproduction