Latin Name: Epalzeorhynchos Pernimius

According to wikipedia:
"Epalzeorhynchos is a small ray-finned fish genus of the family Cyprinidae. Its members are, like some other cyprinids, known as "freshwater sharks" or simply "sharks". They are, however, freshwater members of the Osteichthyes lineage [have bones] which is distinct from the Chondrichthyes lineage of sharks. The description of these animals as "shark" is most likely a reference to the shark-like shape of these cyprinids."

Rocky Mountain Lake Sharks differ from the other species in it's genus in a variaety of ways, most noticably their size. Sightings have claimed specimens up to 3m in length, although generally most sightings are closer to 2m long.

History and Evolution

Based upon observations, annecdotes, and interpretations of native legends, the lake shark as we recognise it today dates back to about the end of the ice age. In glacial lakes a few species of fish adapted to scarce food and fridgid temperatures. Mainly surviving off snow algea and carrion washing out of the glaciers, the fish became the dominant species. They have a natural anti-freeze which lets them be repeatedly frozen without harm. As the glaciers retreated, the fish were left behind in dozens of lakes and streams.

Due to their large size, they were slowly hunted out of lower altitude and easily accessed lakes by natives moving into the area. The legend about the creation of the Columbia Lake and River in the Columbia river valley near Radium BC is clearly a reference to an large lake shark.

Habitat

Lake sharks live in cold and remote medium to large fresh water bodies. High alpine and near alpine lakes with a stream or river leading to other bodies of water are preferred.

Rocky Mountain Lake sharks are sensitive to pollution and therefore very rare near urban centers. They are reclusive in nature, prefering to flee than fight, thus have been chased out of other highly trafficed lakes.

Rather territorial towards their own spicies, larger sharks will chase away smaller and younger sharks. This enforced migration through rivers and streams creates a constantly changing range of habitation which makes tracking incredibly difficult.

Feeding

Lake Sharks are omnivours with a varied diet, and will eat nearly anything they can grab. Their image as a selective eater is only a legend. They are not quite as piscivorous or aggressive as trout, char, or pike. Young lake sharks survive mainly on algea, although insects, fish eggs, smaller fish (up to 1/2 of their length), along with crayfish and other crustaceans make up the balance. As they grow, the proportion of fish in their diets increases, however algea and plankton remain primary food sources. Lake sharks have been observed to eat carcasses, and attack small to medium animals in the shallows near shore. There are persistant rumors of lake sharks attacking humans, but no documented cases have occured. How ever as a general percausion children under 80lbs and pets should stay out of known lake shark habitats.

Length and Weight

As lake sharks grow, they lengthen and increase in mass. The relationship between length and mass is not linear. The relationship between total length (L, in inches) and total mass (W, in pounds) for lake sharks and nearly all other fish can be expressed by an equation of the form:

W = cL^b

b is close to 3.0 for all species, and c is a constant that varies among species. For lake sharks, b = 2.980 and c = 0.000496.

The relationship described in this section suggests that a 13 in (33 cm) lake shark weighs about 1 lb (0.45 kg), while an 39 in (99 cm) lake shark weighs about 27.3 lb (12.41 kg), and a 79 in (200 cm) lake shark weighs about 224 lb (101.82 kg).

Threats and Conservation

Lake sharks populations have declined due to human and natural causes. Lake sharks historically occurred from the Pacific Ocean to the west face of the Rocky Mountains (Alberta), and the southern Yukon/Alaska to northern Idaho.

Rocky Mountain Lake Sharks are endangered under the Federal Endangered Species Act. Lake sharks have been affected by habitat loss due to dams, confinement of streams in concrete channels, water pollution, groundwater pumping, urban heat island effects, and other byproducts of urbanization. Due to their reclusive nature, they have also been chased out of many popular lakes.

*Thank you Rachel for this one (and the whole dang category).