Well, I ended up returning Mr. Mac last night. I had gotten another female krib just 3 days after getting this "pair," younger and smaller. The krib above is chasing her whenever I feed, but she is holding her own. But when MR. MAC got involved, that's where I draw a line - I want both my kribs to thrive and that just won't happen with two fish driving her into hiding. So much for my timid little cichlid!
So back this guy went. I explained what happened and they were trying to figure out who let me get the wrong fish. Happened to be a kid who had only been there 2 weeks at that point - not to get him in trouble but it sounds like they want to educate him a bit. :) He was actually asked to work there as he was a regular customer with some experience and a good kid. He'll learn. :)
I wish I could have a whole tank of kribs! I really love these guys (girls). I am even contemplating setting up a separate tank just to separate these two. The young krib looks like it could be even more of a stunner than the first one, if she grows confident enough to color up. She IS getting some color, and is eating but isn't getting her fair share from what I can see.
Thanks everyone for your feedback!