The pale referred to in the idiom is usually taken to mean the English Pale, the part of Ireland under English rule, and therefore, as perceived by its rulers, within the bounds of civilization. pale see: beyond the pale
For the food, see Salmon as food. The chum salmon (Oncorhynchus keta) is a species of anadromous fish in the salmon family. It is a Pacific salmon, and may also be known as dog salmon or keta salmon, and is often marketed under the name silverbrite salmon.
A betta fish is a small, freshwater fish that is brightly colored, has long fins and is sometimes called a Siamese fighting fish. Male bettas don't like hanging around other bettas and will fluff up their long, flowy fins and fight, sometimes until one is dead.