Sawfish
Sawfish are primarily found in coastal marine and estuarine brackish waters, but they are euryhaline (can adapt to various salinities) and also found in freshwater. The largetooth sawfish, alternatively called the freshwater sawfish, has the greatest affinity for freshwater. For example, it has been reported as far as up the Amazon River and in Lake Nicaragua, and its young spend the first years of their life in freshwater. In contrast, the smalltooth, green and dwarf sawfish typically avoid pure freshwater, but may occasionally move far up rivers, especially during periods when there is an increased salinity. There are reports of narrow sawfish seen far upriver, but these need confirmation and may involve misidentifications of other species of sawfish.
Typhlichthys subterraneus
This species is more commonly known as the Southern cavefish. This name is due to the southern states in which it is found, including Indiana, Alabama, Kentucky, Georgia, Missouri, Tennessee, Arkansas, and Oklahoma. The subterranean waters where the cavefish is found is divided by the Mississippi River. The regions that it occupies include the Ozark plateau of central and southeastern Missouri and northeastern Arkansas, the Cumberland and Interior low plateaus of northwest Alabama, northwest Georgia, central Tennessee and Kentucky, and southern Indiana. It has been observed that the species lives in solitary habitats and is mostly isolated.