Yes we use a ping pong ball to play.. He will rub the inside of the glass if my wife puts her face against the outside. He really tries to touch her. Charlie was less that 2 inches a year ago when we got him.
My syno cat squeaker will let me pick him up and eats food from my hand..I just worry one day he is gonna get freaked by another fish and stick me with one of his barbs again the last sticking was at 4"...he is around 9" now wouldn't wanna know how that felt now.