I recently added 10 aduolt Jewels to a 300 Gal with Oscars, JDs, GT, etc...
The Oscars tried to eat them at first but the Jewels were far too quick... There is a little bit of nipping and chasing away but it's been several weeks now and no mishaps...
I've come to believe that W African Jewels make nice dithers for SA/CA....