Need Some Help with ID and sexing

Hi, I have 2 cichlids in my tank right now - I'm sure that one is a blue male red zebra (metriaclima estherae) - although he's more of a grayish purple with stripes than blue. I think the other is a female - but I'm not sure. I'm attaching a photo of each. I know I need to get a couple more females -- is there anyway to sex young cichlids so that I'm sure to get more females and not more males?

I'm thinking that many pet stores are not going to allow me to grab a fish and vent it - although I do understand that's really the reliable. I was wondering if anybody new if there were any ways to predict, maybe not 100%, whether or not a red zebra is male or female by just looking at it swimming around. If not I may try to find some older ones. Also, does anybody know for sure if the two I've posted actually red zebras?