Marine fish
Marine fish are fish that live in seawater for some or all of their lives. They range from coastal species to animals of the open ocean and deep sea.
Actinopterygii: Ray-finned fishes are the largest class of vertebrates, with fins supported by slender bony rays. Most marine fish belong to this lineage, including many familiar bony species.
Marine fisheries: Marine fisheries are the harvesting of wild marine organisms for food and other products. They turn wild fish populations into a major source of food and livelihoods.
Marine ecosystem: A marine ecosystem is a community of organisms interacting with one another and their ocean environment. Fish are members of ocean ecosystems shaped by habitat, climate, and species interactions.
Freshwater fish: Freshwater fish are fish that live primarily in rivers, lakes, and other low-salinity waters. Their habitats differ in salinity, though some species move between fresh and salt water.
Ocean acidification: Ocean acidification is the decline in seawater pH caused mainly by ocean uptake of atmospheric carbon dioxide. It can affect fish directly and alter the ecosystems and prey they depend on.
Chondrichthyes: Cartilaginous fishes are jawed vertebrates whose skeletons are made primarily of cartilage. Sharks, rays, and chimaeras are marine fish with a distinct skeletal lineage.
Overfishing: Overfishing occurs when fishing removes organisms faster than populations can replenish them. Excessive harvest can deplete marine fish populations and alter food webs.
Marine food web: A marine food web represents feeding relationships among organisms in an ocean ecosystem. Fish act as predators, prey, and links transferring energy through ocean communities.
Anadromous fish: Anadromous fish grow mainly in the sea and migrate into freshwater to reproduce. Their life cycle includes seawater even though spawning occurs in rivers.
Marine heatwave: A marine heatwave is a prolonged period of unusually warm ocean conditions. Extreme warming can shift fish ranges, disrupt reproduction, and intensify ecosystem stress.