In the Mexican cenotes there are Ictalurid catfish that get at least the size of an adult jack dempsey, and seem to hold their own. They resemble our north American bullheads, but a bit thinner, don't think they reach as far south as Nicaragua if you want to be geographically correct.
From a photo of cenote Cristalino, here's one in the lower left corner
And totally incorrect geographically, I keep Synodontus petricola with S and central Amer cichlids, and except during spawning, the cichlids seem to ignore the catfish.
The catfish most commonly found in the Cenotes in Quintana Roo are Rhamdia quelen, which range from Mexico all the way to Argentina. They quite widespread, but unfortunately pretty rare in the hobby.
