What is "saltwater fish"?

Saltwater fish are those that inhabit oceans or other saltwater bodies. They are adapted to survive in high salinity water and often have unique physiological features such as special gills that enable them to regulate salt and water intake. Saltwater fish are diverse and include species such as tuna, marlin, swordfish, sharks, and many types of reef fish. They are an important food source for humans and play a vital role in the marine ecosystem as predators, prey, and scavengers. Some saltwater fish are also popular in the aquarium trade and are kept as pets. However, overfishing and habitat destruction pose significant threats to many saltwater fish populations and conservation efforts are needed to ensure their survival.