Oh really? I've had him for almost 7 months now and he actually seems to be pretty peaceful, even sometimes picked on. But thanks, I will keep in mind!!Probably just algae and I wouldn't worry too much. Just take the ornament out and hose it off.
The black fish is a neon devil/ neon damsel and they get real nasty when they mature. I would return that and get something more peaceful unless you only want that one fish in the tank.