Josh will just be tasked with cleaning the floor around the Biotope entries. It's his penance for having his escaped turtle poop on the floor of the other hotel a few years ago.
It might be good to combine CARES and biotope because it seems like, if you're going to show off a CARES species it'd be good to show off their biotope or set-up that's close enough to it to encourage spawning and general success.
It depends on how people want to enter. Most CARES would probably be in a biotope, but there are so many biotopes possible that wouldn't necessarily feature a CARES fish. I'd almost drop CARES and just go with a biotope.