Still, you clearly have a lot of creative power!
Speaking of creativity, OP, you could print out a picture or a drawing to stick on the back. Even if you need to go to Kinko's or something to get one big enough. (They'd also help with laminating it.) I'm currently backed up on drawings right now, but plenty of forum members around here do drawings, often for free.
I don't know about you, but I have a stockpile of computer backgrounds sitting in a folder. If you search for those, you'll find tons of pictures ripe for use. Black-and-white, fantasy, natural, Japanese, Van Gogh's Starry Night... if you wanted, you could give your fish his own personal Miku Hatsune concert or let him get involved in a Star Wars spaceship battle. Or that one episode of Gravity Falls where they go looking for lake monsters?
You get the idea. The opportunities to be extremely nerdy are extensive here.