Relatively little is known about the diet of the knifetooth sawfish, although it is believed to feed on small fish and invertebrates, such as crabs, squid and shrimps, slashing the saw back and forth to stun or kill prey, or using it to dig for prey in the sand or mud. The saw can also be used in defence against predators such as sharks (2) (4) (5) (8) (9). As in all sawfish, the true teeth in the jaw are tiny, blunt and rounded in shape (2) (4) (9).
The knifetooth sawfish gives birth to between 6 and 23 live young, usually in spring, after a gestation period of several months (2) (4) (9). The young sawfish are quite large at birth, measuring around 40 to 80 centimetres in length (2) (4), and are born with a membranous sheath covering the saw, probably to prevent injury to the mother. The saw hardens and the membrane dissolves shortly after birth, after which the young are able to hunt small prey (4) (9) (10) (11). Little else is known about reproduction in this species, although it is thought to produce a litter only every other year (4) (11). Some sawfish species are believed to live for up to 30 years or more (9).