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.
Longcomb sawfish
The longcomb sawfish has declined drastically and is listed by the IUCN as "Critically Endangered" in its Red List of Threatened Species. The fins (for shark fin soup) and saw (as novelty items) are highly valuable, while some parts are used in Asian traditional medicine and the meat is eaten. Fishing is the main threat, but it is also threatened by habitat loss. Because of the potential threat they (or rather their "saw") represent to humans, they are sometimes killed before being brought onto the boat when accidentally caught. Because of the "saw", all sawfish are particularly prone to becoming entangled in fishing nets.