I say give Harvey some teeth, real nasty ones, then put a metal collar around his neck with a chain connecting him to the back of the cave.
What?
I'm not crazy, honest.
When you guys were kids didn't you dream of having a real life sea monster in your very own aquarium???
Actually, that's how I came to have a lungfish later in life. Since they are considered to be "living fossils" of a sort, it's as close to the real thing as I could ever hope for. If
Coelacanth were legal to own and didn't die in captivity like they do, I'd be all over a custom 200+ gallon tank all decked out with prehistoric rocks, plants, etc.