The polleni and a few Vieja, I don't remember the species of Vieja though (over 10 years ago), believe there were 7 or 8 fish in the 150 at the time, probably a large pleco. They were all 7"-8" fish.
The uros share the cenotes in Mexico with jack dempseys, astynax tetras, catfish, a jade goby, and tons of mollies and other livebearers (which they eat). Some of the adult mollies that live in deeper water, are almost as big as adult JDs.
I am trying to find a compatible catfish for a 3ppt tank. I will update my thread, but there will be large scale changes due to a recent report I found on the effects of hypoxia and salinity on urophthalmus.