Apisto. combrae and borelli are found in the Bella Union (northern) part of Uruguay.
Here are some pictures of Laguna de la Pedrera to give some ideas of what a natural habitat for these fish looks like.
They were breeding in 100-ish degree water in just a few inches of water. The ponds are run-off from sugar cane fields...and feed into the (big) Rio Uruguay.
The apistos share these ponds with everything from cichlids (Gymnogeos and Cichlasoma) to pirahnas, wolf-fish (Hoplias), other characins (Leporinus, tetras, etc.) to Pimelodella catfish.
1) and 2) Laguna de la Pedrera - Apisto. habitats (combrae and borelli)
3) The spilway separating Laguna de la Pedrera from the Rio Uruguay. The far side of the river is Argentina.
Matt