I have kept JD with GT many times and they are good match. Both JD and GT reach maximum size of about 10 inch, and are only mildly aggressive. Who will be the boss depends on individuals and age. I have JD bossed over GT as much as GT bossed over JD. Young JD and GT are more aggressive but will mellow down with age. JD are shy fish and can be skittish. GT are outgoing and never shy. So providing calming tankmates to JD is important. Male GT will develop a big hump with age. Male JD has hardly any hump. As suggested by the mouth shape, JD is more predactory than GT. Both fish came from and do well in hard water.