Abstract: Genypterus brasiliensis, a demersal fish of large size (1.3 m of total length), occurs in the southwest Atlantic (23 to 38oS) and well appreciated due to the quality of its flesh. It was analyzed through longline and trawl fisheries, and the average length and weight of 724 specimens were significantly different between them, with the biggest and heaviest specimens caught by the former. The weight-length relationships were significantly different based upon sex: females Wt=4x10-7Lt3.3799; r2=0.97; n=262; p<0.001, and males: Wt=4x10-7Lt3.3886; r2=0.95; n=190; p<0.001. Using the otoliths readings for 153 specimens (APE of 2% and CV of 4.2%), the growth parameters estimates reveal statistical differences between sexes (p=0.05; r2=0.889). The fisheries were composed of individuals aged 1 to 13 (females) and 1 to 14 years old (males), with ring formation in late spring. The back calculated parameters (VBGF) were: Loo=1,452.38 mm, K=0.0996, t0=-0.2757 yr-1 (females) and Loo=983.07 mm, K=0.155, t0=-0.236 yr-1 (males), and longevity as 29.8 and 19.1 years old, respectively. The low biological production allied to the slow growth and a late complete maturation and its endemism, allow classify G. brasiliensis as a vulnerable resource, jeopardizing a sustainable fishery. Until reliable quantitative biological data are available, precautionary management must be considered.