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.
Catfish
Catfish (or catfishes; order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the three largest species alive, the Mekong giant catfish from Southeast Asia, the wels catfish of Eurasia and the piraíba of South America, to detritivores (species that eat dead material on the bottom), and even to a tiny parasitic species commonly called the candiru, "Vandellia cirrhosa". There are armour-plated types and there are also naked types, neither having scales. Despite their name, not all catfish have prominent barbels. Members of the Siluriformes order are defined by features of the skull and swimbladder. Catfish are of considerable commercial importance; many of the larger species are farmed or fished for food. Many of the smaller species, particularly the genus "Corydoras", are important in the aquarium hobby. Many catfish are nocturnal, but others (many Auchenipteridae) are crepuscular or diurnal (most Loricariidae or Callichthyidae, for example).