In this study we compare the dynamics of artisanal fishery in two adjacent reserves located in the Brazilian Amazon, Mamiraua (being managed for more than 12 years) and Amana (initiating a management process), through the record of 485 fish landings in one fishing community in each reserve during high and low water seasons in 2003. Our goals were, first, to make a rapid and comparative assessment of some main aspects of fisheries in these two communities (fish species caught, CPUE, fishing gear and habitats exploited). Second, we used such data to evaluate if management strategies already in place in Mamiraua would be also valid for Amana . Third, we compared fishing CPUE between the two communities, in order to check if co-management measures have contributed, at least partially, to preclude over-fishing, maintaining a higher fishing reward in Mamiraua reserve. We analyzed fisheries directed to the two most important marketable fishes in the region: the pirarucu (Arapaimas gigas) and the tambaqui (Colossoma macropomum), besides those fisheries aimed to subsistence and lower valued fishes. Our results indicated that the tambaqui was intensively fished year-round in Mamiraua, while Amana fishers caught a higher variety of fishes, including catfishes and migratory scale fishes. Such differences might reflect differences in gear used and habitat exploited by fishers during the high water season. Mamiraua fishers caught a higher fish biomass considering both marketable and all fishes. Differences in gear used, habitats exploited and fishes caught during high water season indicate that distinct management initiatives might apply for each reserve. Notwithstanding their differences, both communities exploited the commercial fishes (tambaqui and pirarucu) in a similar way during the low water season. Therefore, the higher mean fishing yield (CPUE) observed in Mamiraua may be partially attributable to co-management measures, considering that Mamiraua has possibly been experiencing a higher fishing intensity than Amana . Fishing related data are seldom available in Brazil and other tropical developing countries. We thus provided a framework of fast assessment of fishing dynamics, which may represent a first and useful step for management initiatives in the absence of more detailed data.583365376