koi intellegence

How smart are Koi. Basically, are they like gold fish in that they will gorge themselves to death, or do they know enough’s enough. I’m asking this because my koi will ask for food by going to the top of the tank and shaking his head. I know this is about food because he only does this when I am in the room. Anyway is it safe to feed him whenever he does this, or will he over eat?