My EBJD knows whether I'm going to feed or gravel vac based on a) my body position (sitting vs standing) and b) how many people are in the room. If he either sees at least two separate pairs of legs or my face, he knows it isn't cleaning time and starts begging/showing off for food. If all he can see is one set of legs, he's gone.
He also sleeps with the three botia kubotai that are in the growout with him, and kills anything that tries to get near them. I'm not really looking forward to the day I'll have to separate them