The objective of this study was to investigate the effect of the density, on the time of transport with water, during the transport of bullfrog tadpoles (Rana castesbeiana) and to use these results to establish a safe from protocol transport for this species. The tadpoles had been carried in closed system (plastic bag) in different densities until the death of 1st was verified tadpoles or the half death of the tadpoles in each bag. The parameters of quality of the water had been monitored immediately after the closing of the plastic bag. A regression equation was gotten, of the cubical type, involving the density and the necessary time for the death of 1st girino: ?= - 0,000258.X3 + 0,0761.X2 - 7,528X + 262,28 (P<0,01; Adjusted R2 = 89.9%), where ? = time esteem for death of 1º girino (in hours); X = density (tadpoles/L). With this equation, it is possible esteem how much time the girinos could be carried, in accordance with the number of tadpoles for liter.