Altitudinal distribution and body condition of migratory fish juveniles Megaleporinus obtusidens (Valenciennes) and Salminus brasiliensis (Cuvier) in the main channel of the Uruguay River, Southern Brazil.

In this study, we analyzed the altitudinal distribution and body condition of the juvenile migratory fish Megaleporinus obtusidens and Salminus brasiliensis in the Uruguay River, a South American subtropical river. We used the presence/absence data and condition factor (K) of juveniles as indicators to try to characterize some recruitment patterns of migratory fish in the main channel of the Uruguay River. Gillnet sampling was conducted during two reproductive years, 2015-2016 and 2016-2017 (November and March of each reproductive year), in three Uruguay River stretches at different levels of altitude.