The present study comprises the first systematic record of upstream migratory limits for estuarine migratory fish species of the Patos Lagoon basin (Southern Brazil). The Sinos River sampling program included 85 sites sampled from 2004 to 2015, covering lowland stretches and headwaters. The Guaiba sampling program was performed from February 2011 to March 2013, comprising 59 independent samples. Six estuarine migratory fish species are present in upper Patos basin, covering distances in the range of 250-450 km from the Patos Lagoon inlet with the Atlantic Ocean. Parapimelodus nigribarbis comprised animals in the range of 11.3 to 18.9 cm (Median=13.3 cm), corresponding to adult individuals (Sinos: n=459; Guaiba, n=149). The species was captured almost 500 km from the Patos inlet, reaching 180 km upstream in the Sinos main channel. In the Guaiba lake, the species was captured mainly in autumn, although more abundant in Sinos River in winter and spring. Most of Micropogonias furnieri individuals (n=63) were juveniles (10.7-33.4 cm, median=14.2 cm). The species was not captured in Sinos basin. In the Guaiba Lake the species occurred predominantly in the southernmost part (downstream) and was more abundant (>10x) during the winter. Lycengraulis grossidens was captured in Sinos basin restricted to low stretches in summer/spring months (n=7). In the Guaiba Lake (n=134) the species presented widespread distribution all over the lake surface and year around, although ten times more abundant in spring. The majority of the specimens were adults (8.2-26.9cm, median=20.0 cm). Genidens genidens (n=27) was captured only in summer in the southern (downstream) part of the Guaiba Lake. Most individuals were adults (24.5-34.0 cm, median=27.8 cm). Genidens barbus (n=7) was restricted to spring-summer months and was captured only on southern (downstream) segments of the Guaiba Lake, comprising mainly large juveniles and adults (31.5 – 68.0 cm, median=37.9). Mugil liza appeared in spring in relative low abundances (n=13) but was widespread in the entire Guaiba Lake during the summer. The species was not captured in Sinos sampling program. Size profile comprise specimens in the borderline of maturity (34.3-45.5 cm, median=38.9 cm). General descriptive models for fish displacement in the basin are presented.