DD, you have a group of six, correct? If so I would just wait to see if a pair forms and go from there. By then the female may be showing the pink if she's in breeding condition.
Of course venting the fish is an accurate way to sex any cichlid but it's also not a method I'd recommend to Joe Hobbyist or especially to Joe Beginninghobbyist. Most people don't know how to handle them correctly, let alone know what to look for, and the potential to damage the fish is high. The reason we suggest sexing the fish through markings is so that beginner to average hobbyists can do it without stressing the fish.
Yeah, I am saying the odds of having at least 1 female in a group of 6 is pretty good, and which is why I went with 6.... and I am thinking if the belly doesn't turn pink, then I will go with the venting method... I would think that's fool-proof.... I checked the black spots and a couple are just black, and the rest have blue in it.... I checked the pec fins and all of them have some degree of black on them.... I checked the dorsal points and some have the taller one.... and then I checked to see if the dorsal goes past the caudal fin and there is actually 1 that has a pretty long one that goes past the start of it.... so who knows... I just wish there was a solid way to tell.... but I guess not all fish are as cut and dry as guppies, huh...