What you are seeing is "operant conditioning". You are the "conditioned re-enforcer". Or big ugly moving thing (haven't met you, but I would bet we look ugly to fish) comes and then food appears, ipso facto, ugly thing means food. Pretty thing (haven't met her, but momma didn't raise no fool!) comes and no food appears. Therefore, pretty thing is to be ignored. This process has been proven to work on the simplest of life forms. It appears that is one of the building block behaviors that has allowed life to continue and evolve.

I am a falconer and we use the fact that living things respond to reward to train our birds to hunt with us. Pick up a book on operant conditioning or "clicker" training. With a little practice and creativity you could have your fish dancing on cue. And I am not kidding, it really works.