Everytime my son goes with me to the fish store he always wants fancy goldfish and I always have to tell him we don't have a tank for them. I gave in and set up a 30 and got him two fancies. He named them "mailbox" and "water"
My son is three. Mailbox came from the show Blue's Clues. His favorite character is the mailbox and we even had to buy him his own mailbox that he puts letters in and stuff. I have no idea where water came from, who knows what goes through a three year old's mind. I am hoping that from this info you can gather that I am taking care of the fish (goldfish are so messy!!!!) but the tank is in his room.
edit: I'll probably add a little bristlenose sometime, that's his other favorite fish, he calls them "big sharks" and tells all the fish to "watch out for the big shark!"