Abstract In this study, fish oils were extracted from mechanically deboned Nile tilapia ( Oreochromis niloticus ) and hybrid sorubim ( Pseudoplatystoma corruscans x P. fasciatum ) meats. Low-temperature (40 °C) heating and filtration method were used. These oils were evaluated to determine their oxidative and hydrolytic stability during 180 days of storage at −18 °C. The results indicated that storage conditions preserved the quality of both oils for 105 days. Thereafter, the oils gradually underwent hydrolytic and oxidative degradation, reaching acidity indices of 1.67±0.04 and 2.67±0.03 mgKOH/g, and peroxide values of 4.89±0.03 and 3.24±0.05 meq/kg in Nile tilapia and hybrid sorubim oils, respectively.