Length-weight relationship of 12 species of freshwater fish caught in the middle and lower stretches of the Negro River basin, Brazilian Amazon

This study aimed to estimate the parameters of the length-weight relationship for 12 freshwater fish species that inhabit lakes in the Negro River basin (Amazonas state, Brazil). The fishes were sampled using gillnets (15 x 2 m, mesh size 30-100 mm between knots), during the hydrologic cycle: low water (dry), flooding, high water (flood), and receding water, from 2008 to 2010, 2012 and 2013. The gillnets were placed in the lakes with a standardized period of 24 hr, with fish removal occurring every 12 hr (2010 to 2010) and 6 hr (2012 and 2013). Measurements were taken for standard length (SL - 0.1 cm precision) and total weight (TW - 0.1 g precision). The parameters a and b of the equation WT = a.LTb were estimated. This study also provides new data on of maximum lengths for three species.