A total of 108 P. llamasi from the same generation were used in the experiment: 93
mature females measuring more than 50 mm length, and 15 males in the FI (reproductive
form), and measuring more than 60 mm total length. All organisms were produced at
CINVESTAV-Me´rida. The experimental system consisted of 15 plastic tanks of
0.600.340.28 m in a recirculating system with biological filters, individual PVC
shelters and constant water temperature