What you feed can definaltely affect your aro's health. Mine love hikari and crickets, sometimes worms. Most feeders have fat, that fat may be a contributing factor in the fish developing dropeye. Feeder fish can easily have diseases, mine did eat 3 clown loaches, didn't seem to hurt him , but your loach is history if you leave him there, they're like a little flashy lure............
One theory is that feeding feeders develops a higher level of aggression. I think this is true, but we all take care of our aro's a little bit differently.