Their chimples don't look very nice, maybe throw some salt in there, bump up the temp and ensure they have enough space and feel comfortable... you will find out very quickly if they are breeding or not when they start doing their mating dance.
As Bruner247 said, they might just be older or have those colors, darker colors don't always mean mating; but just in case I would be ensuring water parameters are very good so you would have the best chances of breeding and survival. Might also want to look at blackwater extract, or stimulate rainy season with a little cooler water changes.