Some bull trout will remain in the stream for their whole life, while others will migrate to lakes and rivers and even to salt water areas to find food. The male and female leave the eggs, which will incubate for five or six months, hatching in the spring. The fertilized eggs are then covered with gravel. A male bull trout will release sperm to fertilize the eggs. There she will lay as many as 5,000 eggs. The female finds a small, spring- fed stream and digs out a nest in the gravel. Bull trout need cold waters of about 48вЏ (9вЊ) in order to spawn. Most bull trout do not spawn (produce eggs) until they are five or six years old. Bull trout have also been observed eating frogs, As they mature they begin to hunt other fish species, especially mountain whitefish, sculpin, and other trout. The bull trouts' name was inspired by its large head and jaws. Bull trout that live in lakes grow to about 20 pounds (9 kilograms). Bull trout that live their lives in streams are generally quite small at around 4 pounds (2 kilograms). There are many variations of physical characteristics within the species. Generally, bull trout are dark green to brown in color, with pale yellow and red spots and a white belly.

The adult bull trout weighs from 4 to 40 pounds (10 to 18 kilograms) and measures from 1 to 2 feet (30 to 70 centimeters) in length. Range: USA (Idaho, Montana, Nevada, Oregon, Washington Description and biologyД«ull trout belong to a subgroup of the salmon family called 'chars.' Other char species are the lake trout, the Arctic char, and the Dolly Varden, which looks very similar to the bull trout and was once considered to be the same species.