Marine fish are fish that live in seawater. Marine fish can swim and live alone or in a large group called a school.

Marine fish are very commonly kept in aquariums for entertainment. 

Marine aquariums are a multi-million dollar industry in the United States. One way that people are trying to protect the coral reefs is by breeding marine fish in captivity. Captive-bred fish are known to be healthier and likely to live longer. Captive-bred fish are less susceptible to disease because they have not been exposed to the wild and they have not been damaged during the shipment process. Fish that are bred in captivity are already accustomed to aquarium habitats and food.