I just acquired a 4 1/2" -5" Russian that was a rescue by all means.Former owners had it in a 40 high

with much less than optimal conditions.
Food was left out to rot, among other things.
So hopefully I start seeing some growth in this poor beast seeing as it might get bigger.
Plastron is black and flat, are torts dimorphic in this sense like aquatic turtles?
Also, how would I be able to tell if she/he has MBD?
I have vitamins and calcium, how much how often?
I won't waste your time by asking about food, I'll look that up on here.
Just wanted some quick tips for a new acquisition.
Pics to soon follow, nothing you haven't seen tons of times though...