I finally have Ben's filter and air pump all set up and he's thoroughly enjoying his fish tank. His fish even have a new glittering treasure chest decoration enhancing the tank's underwater atmosphere. Have an interesting fish tank is one of the easiest things we can do for Ben. He enjoys it so much and visits it throughout the day. Sometimes these visits are accompanied by flapping and yelling, but sometimes, like this morning, he just pulls up a stool and sits there, watching them. I thought about getting him a more elaborate tropical fish tank set up but once I looked at the main goal - to keep the tank visually stimulating - I decided that simple gold fish were the way to go. 13 cent comets from Petco are amazingly hard to kill. And so, Ben is happy. For now.