If one treatment always feeds first, then the other treatment may get hyped up waiting for you to stop timing the flurry of activity in the other cage. The treatment that eats last may be ramped up and in a more competitive state waiting its turn.
Well...you found one of my training secrets there. Discovered by accident actually. Very good point, and it DOES matter.
If my PVC pipe brackets work as planned, both will be fed at the same time to eliminate this because I tried to train SMB and YP in one of these cages with a divider and one day I noticed after throwing feed to the SMB, the YP were hitting the surface but there was no feed there. It was 10-12 days into it when this happened so I did finish by alternating the feeding. The SMB would occasionally hit the surface but only seldom, the YP went nuts though.
