One word of warning, in the bag pictured above there were 10 belly crawlers, they were added to a 6 ft 100+gallon tank, and within about 2 weeks, the largest one ate all the others, it was a female.
I had picked the bag up at a GCCA (Greater Chicago Cichlid Assn) auction, and a friend of mine bought another bag of 10 the same day, and had a similar experience, only he was left with a male. At about 6 " he gave me his male, at that point they didn't bother each other, originally we were both hoping to end up with a pair.