Fishing is one of the most important economic activities in the Amazon region. In the Lower Amazon, the species Plagioscion squamosissimus commonly known as pescada branca is one of the main commercial species. The objective of this study was to determine the weight-length relationship and the condition factor of “pescada branca” landed at the Fish Market in Santarém-PA. Data was gathered from August 2014 to July 2015 in the Fish Market. The sample had 352 individuals of the species studied. The mean length and mean weight of the individuals analyzed corresponded to 26,83 ± 2.64 cm and 234,87 ± 77, 60 g, respectively. These values generated two equations, namely Wt = 0,0382*Lt2,648 and Wt= 0,1424 *Lt 2,235 for the length-weight relationship for females and males, respectively. The value of b of length-weight ratio was < 3, thus the growth of species can be considered negative allometric for both genders. The annual variation of the condition factor suggests that fat accumulation occurs in the period of drought / flood. This estimation is of great use for the management of the pescada branca stocks and can provide subsidies for decision-making administratos, in order to promote the conservation and rational use of the fishery resource. Keywords: fishing landings; biological estimates; fisheries management.