We have kept and bred the red jewel, they were atrocious.. they were in a 4 ft tank before we took them out to breed in their own tank, and the tank mates (not peaceful communals) were smacked up against the opposite end of the tank, too scared to move, the jewels once paired up decided to own the full tank as territory, of which is often the case, that is why they were moved ,especially when the babies are ready to travel with mum and dad will they attack anything in sight. Alot of sites on the net advise that the jewel be kept in a monospecies aquarium or with species that can pack as much punch as they can themselves. Definately not to be kept with delicate fish. I wouldn't risk it anyway.