IMO, if you like
Mesonauta, it's best not to think too much about the specific species. They are notoriously hard to identify and the differences usually come down to little things like fused bars, reticulated scales, and the longitudinal stripe that runs into the dorsal.
I have grown out two groups of wild juveniles purchased from Jeff Rapps. The first was sold to me as
M. acora and the second as true
M. festivus from Rio Tapajos. Both groups varied from fish to fish. There were silver fish in both groups and yellow fish in both groups. In the
M. festivus group, the females turned yellow with dark black bars when spawning, taking on a bumblebee appearance. When they weren't spawning, the yellow faded and they went back to being silver fish with a black longitudinal stripe across the body.
I posted pictures of both groups as juveniles and adults on various cichlid forums and everyone told me they were something different. I literally had five different people identify the first group as five of the six described species. It got me nowhere.
There are slight differences in body shape and color in some of them, but I don't even think that has to be specific to the species of fish. I think they are highly variable within a group, just like things like severums and discus. Buy a group and grow them out. I find that they're usually enjoyable regardless of the species.
Also, regarding Wet Spot's listing, they are just using a generic name. A lot of people list them as
Mesonauta festivus because that was a catch-all name for them, stemming from their old classification as
Cichlasoma festivum. It's the same reason so many people erroneously list green severums as
Heros severus, which comes from
Cichlasoma severum. Those are outdated names that stick around in the trade as a general catch-all for multiple species in a single genus.
Here are some of my two different groups.
