Coalfish is a type of fish that belongs to the family Gadidae. It is also referred to as saithe, pollock, or Boston bluefish, and it is popular in many European countries. Saithe has a strong and distinctive flavor that is slightly sweeter than cod, but not as mild as haddock. Pollock is a close relative of coalfish, and it is popular in North America and Asia. It has a milder flavor compared to coalfish, and it is often used in fish and chips. Boston bluefish is a colloquial term that refers to a type of coalfish that is popular in the United States. It is called bluefish due to its blueish-black skin.