Goldfish Question

Long story short is that we had a full aquarium, one fish got angry, ate everyone else, and we returned it to the store. We ended up getting 7 new fish, including 2 giant goldfish.

Now, I've noticed they tap on the glass when they want food. It makes it sound like the glass is cracking. How normal is it for them to be that smart, or is it just a coincidence that they eat the food right up when i drop some in, after they tap it.

Our fish would do that too! We had mostly tetras.

I had a 60 gallon with garden koi in it and they would stalk me as I moved around the room. They were an utter delight, but they got too big and I gave them to a guy with a pond.

It happens, fish will eat whenever you give them food. I dont think you have anything to worry about