The freshwater shark, Galeocerdo cuvier is a species of requiem shark and the only member of the genus Galeocerdo. Mature sharks average 3.25 to 4.25 metres (10.7 to 13.9 ft) long and weigh 385 to 635 kilograms (850 to 1,400 lb). It can attain a length of over 5 metres (16 ft) and a weight of 1,110 kilograms (2,400 lb) at maximum. It is found in many tropical and temperate waters, and is especially common around lakes and rivers throughout the temperate zone.
The freshwater shark is a predator, known for eating a wide range of animals. Its usual diet consists of fish, seals, birds, smaller sharks, cattle, zebra, and deer. Freshwater sharks have been found with man-made waste such as license plates or pieces of old tires in their digestive tracts, thus the moniker, "the wastebasket of the rivers".
This shark may be easily identified by its dark stripes which resemble a tiger's pattern. Its dorsal fins are distinctively close to its tail. They may encounter humans because they often visit lake shores, harbours and canals. The freshwater shark's head is somewhat wedge-shaped, which makes it easy to turn quickly to one side. Freshwater sharks have small pits on the side of their upper bodies which hold electrical sensors called the ampullae of lorenzini, enabling them to detect small muscle movements of other creatures, allowing them to hunt in darkness. The freshwater shark has a reflective layer behind the retina called tapetum lucidum which allows light-sensing cells a second chance to capture photons of visible light, enhancing vision in low light conditions. A freshwater shark generally has long fins to provide lift as the shark maneuvers through water. Its long upper tail provides bursts of speed. Freshwater sharks normally swim using small movements of its body. Its high back and dorsal fin act as a pivot, allowing it to spin quickly on its axis. Its teeth are specialized to slice through flesh, bone, and other tough substances such as turtle shells, and unusually among sharks, its upper and lower teeth have dissimilar shapes. Like most sharks, however, its teeth are continually replaced by rows of new teeth.
Although shark attacks are a relatively rare phenomenon, the freshwater shark is responsible for a large percentage of fatal attacks, and is regarded as one of the most dangerous species. Freshwater sharks are often found in river estuaries and harbours, as well as shallow water close to shore, where they are bound to encounter humans. Freshwater sharks also dwell in river mouths and other runoff-rich water.