Males don't always have dots on top of their tail fins.
The femsales do have a reddish/purple belly but males can have this too. Females tend to have brighter ones.
Males are usually a good bit bigger and they are slim in shape whereas females are much more rounded. Males tend to have longer fins as well.
The one at the front/bottom is a male. The one at the top/back is a female.
Oh, and so what do you have, male or female?
I had a male and a female before - the male bullied the female really badly. I returned him to the fish store, but it was too late and she later died of stress. I however, have had really bad luck with cichlids. Many recommend that if you are keeping any african cichlids together, like kribs, that you keep a lot, and have 2-3 females for every male. I'm not saying it wouldn't work, I'm just saying keep a very close eye on them. If your female looks like she has nipped fins, or appears stressed, it's time to return the new one unfortunately.