Abstract The behavior of two Castor oil based muds (OBM) prepared with additives marketed in Colombia is observed, the concentrations of the additives are the same for both fluids with the difference that one has as rheological modifier a polar activator and the other uses lime. These ones are subjected to rolling up for 16 hours at temperatures of 65°C, 80°C and 120°C. The rheological behavior of the fluids is analyzed according to API RP 13B-2 standard before and after rolling up at different temperatures. According to the results of this investigation, it is discovered that the fluids behavior in the presence of strong bases like lime becomes stable as the rolling up temperature increases until 120°C, whereas when there is no lime in the composition the behavior is more constant in all the cases and the change of viscosity with respect to the initial viscosity is smaller. The presence of strong bases tends to decrease their percentage of fatty acids 17% at 65°C and increase 6% at 120°C with respect to the fluids with polar activator rolled up at the same conditions. To see if the fluids can be categorized as environmentally friendly, we proceeded to evaluate the impact of the fluids developed in the survival of red tilapia fingerlings in a water body simulated in the laboratory. The minimum conditions to die at least 50% of the population of red tilapia fingerlings was 96 hours of exposure to fluids at a concentration of 5000ppm.