Some these guys ranging down as far south as southern central America are North American.
Now to the important stuff. I recently got back into cichlids after nearly a decade of abstinence. Current interest is on some Chuco micropthalmus of Costa Rica acquired from an cichlid supplier in St. Louis, MO (Malawi Aquatics). I acquired to juveniles 1" and 1.5" long. Over last few days I noticed pits in the sand that were shallow and round. The cichlids were seen in the pits but I did not observe their construction efforts until today. They dig pits in much the same way a Convict Cichlid or Longear Sunfish moves substrate using their pectoral fins. The latter two species do it to exposed prey items under detritus or otherwise loose substrate. I am not so certain the C. micropthalmus are doing it for the same reason. The C. micropthalmus are making deeper pits and spending a lot of time in them. Color pattern they exhibit changes while in the pits. They also may be roosting in the pits at night.