To improve the parameters of the transesterification process by the basic route for the production of biodiesel, crude fish oil (AP), obtained from the viscera of fish, and residual vegetable oils (AR) blenders were used. Because the AP contains high percentages of long chain polyunsaturated fatty acids that are responsible for its instability is that it was mixed with increasing percentages of AR. This translated into a higher conversion performance to biodiesel by the basic route, also depending on the level of free fatty acids. The index of methyl esters obtained from the blends and the original oils was analyzed. The calculation of the performance of each reaction is made based on the produced esters. The analysis is complemented by measuring the kinematic viscosity of the blends and the pure oils, as well as the biodiesel produced. The results showed yields higher than 90% when using the process of transesterification of the blends by the basic route. The standardization of blends by its acidity index is of great importance reaching a maximum value of 3.5 mgrKOH / gr. On the other hand, the viscosity of the biodiesel produced, from the blends, is kept within international standards; In addition, the process conditions are improved.