Home > Online Learning Center >Freshwater Sawfish

Conservation Status:  Endangered

AquaticFreshwater Sawfish

Pristis microdon Cartilaginous FishesRays

Aquarium of the Pacific - Online Learning Center - Species Print Sheet

Freshwater Sawfish
the sharp tooth-like structures of the sawfish's saw | Photo taken by K. Leonard. © Aquarium of the Pacific
Freshwater Sawfish
Our sawfish in the Aquarium's Shark Lagoon habitat | © Aquarium of the Pacific

Species Overview

Pristis microdonis one of eight species of sawfish in the genus Pristis. It has two common names, the freshwater sawfish and the largetooth sawfish. The latter common name is also used for three other species in the genus. Freshwater sawfish are rays, and are related to stingrays, skates, sharks, and other fishes with cartilaginous skeletons.

Previous Image |

Species In-Depth | Print full entry

At the Aquarium

Shark Lagoon is the habitat for our sawfish. Dinner is fed to this ray attached to the end of a pole. Because the nurse sharks also like mullet and try to steal the sawfish’s dinner, they have to be distracted when the sawfish is being fed.

Geographic Distribution

East Africa to Indonesia, India, the Philippines, New Guinea, and Australia.

Habitat

These rays are found in shallow marine coastal waters, rivers, estuaries and lakes, preferably with sand or mud bottoms.

Physical Characteristics

The freshwater sawfish’s body resembles that of a compressed shark with large flat pectoral fins, two almost equally sized dorsal fins, and a shark-like tail. Its eyes and two small holes (spiracles) are on the top of its head. Nostrils, mouth, and gill slits are on the ventral (under) side of the ray’s body. The sawfish’s most distinctive identifying feature is a broad, slightly tapering snout with heavy, pointed, razor-sharp, tooth-like structures equally spaced along each side. The snout which looks like a coarse toothed saw, known as a rostral saw, is about 1/4 to 1/5 the total length of the fish.

The sawfish’s upper surface is commonly a muddy brown color, but may also be dark green or gray. The underside is creamy white. This type of coloration is called countershading.

Size

The maximum length of these fish is about 6.5 m (21 ft). It can weigh as much as 600 kg (1320 lb).

Diet and Feeding

Their diet consists primarily of small fishes and a variety of mollusks, crabs, and other invertebrates. The saw has many small sense organs that help the animal find food, especially in sandy and muddy bottoms.

Reproduction

It is believed that these sawfish reach sexual maturity at about 10 years. These animals are ovoviviparous (producing eggs that develop and hatch within the female’s body without obtaining nourishment from her). Fertilization is internal and the mother gives birth to live young after a five months gestation. The average litter size is about eight pups. Pups are 75 cm (2.5 ft) at birth.

To protect the female as a pup emerges from her uterus, the pup’s saw is flexible and covered with a sheath of heavy fibrous tissues. Shortly after birth the saw hardens and, with normal use, the fibrous sheath wears away.

Behavior

Sawfish are rather sluggish and slow swimming.

Adaptation

The sawfish is an osmoregulator, i.e., it is able to adapt to living in salt, brackish, and fresh water.

This fish’s “saw” is an important tool that has become adapted for both feeding and as a formidable defensive weapon. The sawfish defends itself against fish much larger than itself, often inflicting lethal wounds with its saw. Swimming into a school of fish, it swings its saw rapidly from side to side to impale, stun, or kill fish in the school. It scrapes fish caught on the saw against the bottom to dislodge them for a meal. It retrieves the fish that are left dead or wounded on the bottom to eat at its leisure. The saw is also used as a digging tool to probe in mud and sand in search of crustaceans and other small invertebrates.

Longevity

Life span is estimated to be from 19 to 30 years.

Conservation

The IUCN Red List lists the freshwater sawfish as an endangered species. Never found in large numbers, its population has decreased alarmingly in recent years. All species of sawfish worldwide are listed as either endangered or critically endangered. Over fishing, pollution and habitat degradation due to coastal development over most of their ranges are major factors in population loss. The freshwater sawfish has been targeted as a food fish and the saws have been sold as souvenirs. They are sometimes caught as bycatch in nets set for smaller fish.

Amazing Facts

Sawfish are often confused with sawsharks which have a similar snout. However, the sawfish is much larger and its gill slits are on the ventral (bottom) side of its body. The gill slits of the sawshark are on the side of its head.

Additional Images

Freshwater Sawfish
the sharp tooth-like structures of the sawfish's saw | Photo taken by K. Leonard. © Aquarium of the Pacific