I had problems trying to keep a smaller male JD in with a larger male gold saum in a 55gal. One night the JD just snapped and tore off 10-20% of the GT's scales. Adding a divider was the only thing that saved the GT. GTs are bullies, but really can't back it up as well as almost any CA cichlid can. Tried the GT with a male convict and had the same issues. Then again the convict and JD were VERY aggressive in other tanks, so it's possible that you may find a more laid back JD.