Fresh Nile tilapia (Oreochromis niloticus) and hybrid sorubim (Pseudoplatystoma corruscansP. fasciatum) harvested from a local f ish farm during the summer, were supplied by a local federal inspected fish processing plant. The aquaculture fish was feed twice a day with commercial feed containing 40% of crude protein and 12% crude fat until they had average weights of 0.7070.03 kg for Nile tilapia and 0.8570.03 kg for hybrid sorubim, after 6–7 and 9–10 months, respectively. About 100 fish of each specie was mechanically eviscerated under vacuum (without manual contact)