Fighting fish is a term used to describe a variety of species of fish that are known for their aggressive behavior. The most common type of fighting fish is the Betta, which is a small freshwater fish native to Southeast Asia. Bettas are popular in the aquarium trade and are known for their vibrant colors and long fins. Another type of fighting fish is the King Mackerel, which is a large saltwater fish found in the Atlantic Ocean. King Mackerels are known for their powerful swimming abilities and are often used as game fish.