To me the 1st pic looks female (a very dominant one indeed), although most Herichthys pairs take on identical colors when spawning.
It may be that the most colorful one is a dominant female, and they are simply in a lesbian relationship.
All kidding aside, I have had a few female pairs spawn wth each other.
In the absence of a acceptable dominant male,I believe females spawning together will help them get rid of eggs, in so prevent them from being killed if egg bound.
That said, the male carpintus on the right below, has almost idententical colors to the female when guarding a spawn.
I've had female HRP pair up. I am assuming females pairing up is a result of unnatural contditions in an aquarium.
Thanks for info and pic. Caprintis is a very similar species.
