Summarize this article:

Farmed salmon is the term for the mass raising of salmon. These salmon are kept in small pens and fed diets containing hormones, dyes and antibiotics. They are often grown in deplorable conditions which facilitate the spread of disease and lice among the fish population. This salmon, however, is widely available and inexpensive. You should not consume farmed salmon more than one time per month due to the high level of chemicals in the fish. Wild caught salmon is the most expensive of all the kinds. This is because the fish are allowed to grow at their own pace in a natural environment until caught or harvested. The harvest of wild salmon is strictly monitored and regulated with the aim of stabilizing or increasing the number of available fish. Wild salmon from Alaska is considered to be a sustainable harvest, due, in part, to the strict regulations and the fact that the fish is allowed to reproduce as naturally.

Summary:
Buy farmed salmon. Buy wild salmon.