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.
Sawfish
Sawfish have a strong shark-like body, a flat underside and a flat head. "Pristis" sawfish have a rough sandpaper-like skin texture because of the covering of dermal denticles, but in "Anoxypristis" the skin is largely smooth. The mouth and nostrils are placed on the underside of the head. There are about 88–128 small, blunt-edged teeth in the upper jaw of the mouth and about 84–176 in the lower jaw (not to be confused with the teeth on the saw). These are arranged in 10–12 rows on each jaw, and somewhat resemble a cobblestone road. They have small eyes and behind each is a spiracle, which is used to draw water past the gills. The gill slits, five on each side, are placed on the underside of the body near the base of the pectoral fins. The position of the gill openings separates them from the superficially similar, but generally much smaller (up to long) sawsharks, where the slits are placed on the side of the neck. Unlike sawfish, sawsharks also have a pair of long barbels on the rostrum ("saw").