Miniatus Grouper
 

I have one Miniatus Grouper that has been in a 200 gallon tank for about 6 months with a Zebra Eel. Just the other day i came across another Miniatus that has different coloration in that the spots are green-ish and not blue like my current one. Both of the fish are the same size. Is there any way to sex these fish? What would be my odds of these fish fighting upon introduction?

In my experience Miniatus will not tolerate other groupers in the tank, let alone the same species.