No, unfortunately I do not know. I have four of them in this tank, and I have one that is hidden in the center cave almost always (you can see "his" silhouette in a pic in my gallery - he does not come out often) and I can only assume he is the dominant male. It is interesting because he is probably 3/4-inch larger than the other three in the tank, yet he is the very last one to come out at feeding time, and he seems to eat the least.
Calvus are so slow to mature so though I hope I have a male and three females (a harem would be the coolest) I can't be certain, probably for another 6 months. Every once in a while one of them gets driven to the topmost corner, and that is why I have a piece of java moss wadded in a top corner to provide cover, but after a few days they come back down and hang in the plants and rocks again. Very interesting. Usually when a cichlid gets driven to a top corner, that is all she wrote, and the fish has to be removed. Not so here, and I am grateful, since I'd have to set up another tank! 8O
The tank is a room divider next to my desk, so I get to watch them constantly during the day. It is a wonder I get anything done.