Stone Cold,

Never had the Southerns (black) but have kept the Northerns (gold)! I've had friends however that have kept the blacks! From what I know, the blacks get bigger and are a little bit more irritable than the golds! From what I remember, my golds, were somewhat gold as hatchlings as the black hatchlings were almost axanthic forms of mine! I do know, that both forms need to be 5-6 years old before reach sexual maturity! Hope this helps!