Use any fish model you like, or make your own. Just remember, it needs to be robust enough to stand up to some handling. I tried a full-color print in sandstone, but it's so brittle, I didn't want to take a chance breaking it.
When I saw Mr. Fish by Chuck Norris,
I knew he was the one..! I used an Objet Connex at Autodesk. This guy is pretty simple, so a Makerbot should work totally fine.