The bull trout, of the genus Salvelinus, is an endangered species of fish belonging to the Salmonidae family, along with the salmon, char, and other types of trout. It was originally in the same class as the Dolly Varden, but was distinguished from that species in 1980. Though their name includes the word "trout," the bull trout is actually classified as a char. This type of fish is native to the northwestern section of North America.
Bull trouts get their name because their head and mouth are larger than most other types of fish in the Salmonidae family. These fish vary in size depending on their location. Those found in large bodies of water can measure 24 inches (61 cm) and weigh 20 pounds (9 kilograms) or more. Bull trout living in rivers and streams tend to measure 14 inches (36 cm) and only weigh approximately 4 pounds (1.8 kilograms).
The back of the bull trout tends to be a dark shade ranging from green to brown, which fades to white on the fish's belly. Their backs are also typically covered in light colored spots which can range from a yellow to red shade. When adults begin to spawn, they may gain red spots on their underbellies as well. Bull trouts are very similar to the Dolly Varden in colors, but are typically larger and have a broader head than the other fish.
Sexual maturity of the bull trout is generally reached at five to seven years. They typically spawn during the fall months as the water gets colder. The female creates the spawning site while the male keeps fish and other predators away. Incubation for bull trout eggs are longer than that of other members of the Salmonidae family, as they do not begin to hatch until late winter or early spring.
Bull trouts are quite picky when it comes to their habitat. They typically prefer cold water, with the temperature falling below 55 °F (13 °C). Clean, deep pools tend to be the ideal place for these fish to spawn and live. They also tend to select areas that have many small channels accessible for when they need to migrate.
Young bull trouts generally feed on plankton and insects. As they get older, they tend to switch to other fish, such as other trout, herring, whitefish, and salmon. Some large bull trout have been known to consume mice, frogs, and snakes.