With frequent new discoveries, the number of valid scientific descriptions of species of fishes is always on the upswing. Projections from 2006, self-described as conservative, put the eventual number of living species to be close to 32,500. Fishbase.org, updated in April 2009, has a searchable database of 31,200 species.
77 A.D. – ~144 known species
1976 – 18,818 known species, 450 families
1984 – 21,723 known species, 445 families
1994 – 24,618 known species, 482 families
2006 – 27,977 known species, 515 families
Of the total species formally described in 2006, 42.7% (11,952) of species live in freshwater, 55.5% (15,520) of species live in seawater, and 1.8% (505) of species move between freshwater and oceans during their lifecycles.
- The largest order of fishes is Perciformes that is comprised of 10,033 species, and includes 160 families. Perciformes include fresh and salt water fishes such as gobies, wrasses, sea basses, and cichlids.
- The smallest orders of fishes is Amiiformes with only 1 specie. The Amiiformes order is comprised solely with the bowfin, Amia calva which is distributed over the eastern half of North America.
- The greatest diversity geographically is found in the tropics, with the most marine species found in Indo-West Pacific (western Pacific Ocean, Indian Ocean, Red Sea), and the most freshwater species located in Southeast Asia, South America, and Africa.
- The fish found at the highest altitude is the nemacheiline river loach that inhabits hot springs in Tibet at an elevation of just over 17,000 feet (5200 meters).
- At 26,246 feet (8000 meters) below the surface of the ocean, the cusk-eels are the deepest living fishes.
- Of the total described species, 970 are cartilaginous sharks, skates, rays and chimaeras.
- The largest living fish is the whale shark which can grow over 40 feet (12 meters) long.
- One of the smallest fish and vertebrate known, with the smallest mature female measuring just 7.9 mm is the Indonesian minnow Paedocypris progenetica.
Nelson, J. S.: Fishes of the World, John Wiley & Sons, Inc. 2006
Helfman, G.S.: The Diversity of Fishes, Blackwell Science, Inc. 1999