I love watching them at someone else's home.
My DD wants one, just know that she will try to play with it. Will have to have a serious talk before that happens. Koi can get really tame though.
My nephew (4) put some chicken spice on their food to make it nicer. He also put the TV remote in the tank for them in case they wanted to watch TV while he was at school.
Some of them survived all that kindness...