Salmon is the common name for fish in the order Salmoniformes. They live in the northern Atlantic and Pacific oceans, and are anadromous, which means most types of salmon are born in fresh water (rivers or streams), migrate to the sea and live much of their lives in salt water, and return to freshwater to reproduce, or "spawn". Salmon appearance varies greatly from species to species.
Species like Atlantic salmon have black spots on their sides. Most of these species maintain one color when living in fresh water, then change color when they are in salt water. all Pacific salmon and up to 50% of other species die within a few weeks. The salmon that do not die can spawn two or three more times.
Salmon is a popular food. Classified as an oily fish, salmon is considered to be healthy due to the fish's high protein, high omega-3 fatty acids, and high vitamin D content.
Salmon is also a source of cholesterol. Farmed salmon has a high omega 3 fatty acid content comparable to wild salmon. 

Salmon flesh is generally orange to red, although white-fleshed wild salmon with white-black skin colour occurs. The natural colour of salmon results from carotenoid pigments, but also canthaxanthin, in the flesh. Wild salmon get these carotenoids from eating krill and other tiny shellfish.
Salmon is not only tasty but has considerable health benefits; when baked, broiled, seared or grilled, salmon is among the most heart-healthy of dishes

Source of Omega-3 Fatty Acids
Omega 3 fatty acids are a type of essential fatty acid. The body cannot make them on its own and requires intake from food or vitamins in order to supply the nutrients. Omega 3 promotes healthy joints and skin, reduces the risk of heart disease and aids in neurological development in unborn children. Atlantic salmon has the highest concentration of omega 3 in the salmon family. According to the Worlds Healthiest Foods, omega 3 improves heart muscle function and reduces the risks of deadly heart arrhythmia.

Vitamin B Rich
Salmon provides a good source of some essential vitamins you need for a healthy lifestyle. They can be included vitamin B-12, B-6, B-3, B-2, niacin, thiamin and pantothenic acid. Vitamin B-12 is important for energy metabolism, supporting proper function of the nervous system and forming new cells.
 Vitamin D promotes healthy bones and teeth, and may help decrease your risk of developing multiple sclerosis and certain types of cancer. The protein found in salmon helps the body maintain metabolism at levels to promote
weight loss. 

Source of Minerals
Most varieties of seafood are rich in minerals, particularly the trace mineral selenium, and salmon is no exception. A low intake of this mineral may contribute to reduced immune function, increased risk of developing cancer as well as increased susceptibility to viral diseases.
Salmon is a source of the major minerals phosphorus and potassium. Phosphorus is needed to build and maintain strong bones. Potassium is important for regulating heartbeat and maintaining healthy blood pressure. Another mineral is selenium. Selenium may fight heart disease, cancer, mental decline that comes with age and thyroid disease.