as of now i only have 1 golden moray eel, sohal tang, red sea purple tang, magnifient foxface, many hundreds of hermits and snails... so far hardiness and lifehood of these livestock are living well. just decided to add another to beuatify a brilliant species...
The Dragon moray is a fish eater and will ingest anything that can fit into its expandable jaws. Keep singly except in mated pairs. Prone to escaping from open tanks. My best opinion on mixing two different eels is risky at best. not to say you cant do it with plenty of room and hiding places. Is a 500g system big enough? well maybe, maybe not. I would think not long term. only my two cents. Others will probably weigh in here. good luck. your inquiry posses an interesting thought. keep us posted.