Most of the fishes eaten by humans are ray-finned fishes, such as salmon, trout, tuna, flounder, catfish, cod, and bass. While some ray-finned fishes are tiny, an ocean sunfish can weigh as much as 5,000 pounds. Including about 29,000 species in more than 400 families, ray-finned fishes provide plenty of options for human consumption. A handful of species are cultivated on fish farms for commerce that totals billions of dollars annually. Ray-finned fishes, such as goldfish and tetras, support a high-value pet commerce as well. Unfortunately, many populations of ray-finned fishes are threatened by overharvesting, introduced species, water pollution, and other impacts to their habitats. While most extinctions have been of freshwater species, ocean species such as tuna have suffered severe declines. Several hundred species of ray-finned fishes are in danger of extinction (endangered), while more than 500 species are vulnerable to endangerment.