Trout is the name given to fresh water and marine water fishes belonging to the family Salmonidae. They are classified as oily fish. Trout prefer to live in different habitats and bear different colourations and patterns. Most colours and patterns are used as camouflage as they are based on the surroundings and will change as the fish moves to other habitats. Trout while returning to the sea acquire silvery white colouration resembling the fishes of small streams and alpine lakes. It is very difficult to trace out the colours and patterns of a particular species of trout. Wild trout have more vivid colours and patterns. gear for the fishing
The fins are without spines but a small well demarcated adipose fin is present at the back near the tail. There are many species known but all populations differ from each other morphologically. Trout of eastern United States are good example of this. The brook trout, aurora trout and the silver trout all have different physical characteristics and colourations that distinguish them but the genetic analysis shows that they all are one species. Lake trout inhabits the larger lakes of North America and live longer than the rainbow trout which have an average lifespan of 7 years. Lake trout are able to live for many decades and can attain a body weight of about 38 kg. Trout usually dwell in cool, clear streams and lakes although few species are anadromous also. Young trout are designated by the term troutlet, troutling or fry. They are distributed in North America, northern Asia and Europe. Several species have been introduced in Australia and New Zealand by the fishing enthusiasts in the 19th century which made many native fishes to enter the category of endangered. The introduced species include the brown trout from England and rainbow trout from California.
Trout prey on other fishes, invertebrates, mayflies, caddisflies, stoneflies and molluscs. Zooplankton also forms a very important part of the diet of trout when they dwell in lakes. Larger sized trout usually prey on fishes. Adult trout are known to devour fishes about 1/3rd of their length. They also feed on mealworms, shrimps, bloodworms and eels. They are important food fishes and their flesh is considered to be very tasty. The flavor of the fish is highly dependent upon the diet of the fish. For example, those feeding on the crustaceans are tastier than the one feeding on insects. They can be easily caught by reel and rod. Farmed trout are commercially sold as food fish. According to a report of British Nutrition Foundation the flesh of trout contains lesser percentage of dioxins in comparison to other oily fishes.