Fish, RAI-TRO
Fishes have been in existence for more than 450 million years, and they have evolved to fit into almost every conceivable type of aquatic habitat, including both fresh and salt waters. Almost all natural bodies of water bear fish life, with the exception of very hot thermal ponds and extremely salt-alkaline lakes, such as the Dead Sea in Asia and the Great Salt Lake in North America. Although most fish species are cold-blooded, one especially contrarian species, the opah (Lampris guttatus), is warm-blooded.
Fish Encyclopedia Articles By Title
rainbow trout
rainbow trout, (Oncorhynchus mykiss), game fish of the family Salmonidae noted for its spectacular leaps and hard......
rasbora
rasbora, (genus Rasbora), any of a group of about 45 species of schooling freshwater tropical fishes in the carp......
ray
ray, any of the cartilaginous fishes of the order Batoidei, related to sharks and placed with them in the class......
redfish
redfish, (Sebastes norvegicus), commercially important food fish of the scorpionfish family, Scorpaenidae (order......
reedfish
reedfish, (Erpetoichthys calabaricus), species of air-breathing eel-like African fishes classified in the family......
remora
remora, (family Echeneidae), any of eight species of marine fishes of the family Echeneidae (order Perciformes)......
Rhipidistia
Rhipidistia, extinct group of lobe-finned bony fishes of the order Crossopterygii that included the ancestors of......
ribbonfish
ribbonfish, any of several species of deep-sea, marine fishes constituting the family Trachipteridae (order Lampridiformes).......
roach
roach, (Rutilus rutilus), common European sport fish of the carp family, Cyprinidae, widely distributed in lakes......
roosterfish
roosterfish, (Nematistius pectoralis), popular game fish of the family Nematistiidae, related to the jack (q.v.)......
rudd
rudd, (Scardinius erythrophthalmus), stout-bodied freshwater sport fish of the carp family, Cyprinidae, similar......
runner
runner, any of certain species of fishes in the family Carangidae (order Perciformes), which also includes the......
sailfish
sailfish, (genus Istiophorus), (genus ), valued food and game fish of the family Istiophoridae (order Perciformes)......
salmon
salmon, originally, the large fish now usually called the Atlantic salmon (Salmo salar), though more recently the......
salmon shark
salmon shark, (Lamna ditropis), species of mackerel shark (Lamnidae) whose geographic range spans the entirety......
sand lance
sand lance, any of about 18 species of marine fishes of the family Ammodytidae (order Perciformes). Sand lances......
sand shark
sand shark, any of three species of sharks of the genera Carcharias and Odontaspis in the family Odontaspididae.......
sand tiger shark
sand tiger shark, any of three species of sharks classified in the genera Carcharias and Odontaspis in family Odontaspididae......
sanddab
sanddab, any of certain edible, American Pacific flatfishes of the genus Citharichthys (family Paralichthyidae).......
sandfish
sandfish, any of several unrelated marine fishes found along sandy shores. Sandfishes, or beaked salmon, of the......
sardine
sardine, any of certain food fishes of the herring family, Clupeidae, especially members of the genera Sardina,......
saury
saury, any of four species of long, slim marine fishes of the family Scomberesocidae (order Atheriniformes). Sauries......
Saving Sharks in the 2020s
Shark finning is the harvesting of a shark’s lateral, dorsal, and lower tail fins, which is often followed by releasing......
saw shark
saw shark, (order Pristiophoriformes), any of about nine species of long-snouted marine sharks belonging to the......
sawfish
sawfish, (family Pristidae), any of five species of sharklike rays forming the genera Pristis and Anoxypristis......
scad
scad, any of several species of fishes in the family Carangidae (order Perciformes), which also includes the jacks,......
scaleless dragonfish
scaleless dragonfish, any of the more than 180 species of marine fishes constituting the subfamily Melanostomiinae......
scat
scat, in biology, any of four species of fishes constituting the family Scatophagidae (order Perciformes). The......
scorpaeniform
scorpaeniform, (order Scorpaeniformes), any one of a group of bony fishes that are characterized by a plate of......
scorpionfish
scorpionfish, any of the numerous bottom-living marine fish of the family Scorpaenidae, especially those of the......
sculpin
sculpin, any of the numerous, usually small fish of the family Cottidae (order Scorpaeniformes), found in both......
sea bass
sea bass, (family Serranidae), any of the numerous fishes of the family Serranidae (order Perciformes), most of......
sea dragon
sea dragon, any of three species of small slow-moving bony fishes classified in the genera Phyllopteryx and Phycodurus......
sea lamprey
sea lamprey, (Petromyzon marinus), eel-like, jawless species of fish native to the North Atlantic Ocean, Gulf of......
sea robin
sea robin, any of the slim bottom-dwelling fish of the family Triglidae, found in warm and temperate seas of the......
seahorse
seahorse, (genus Hippocampus), any of about 50 species of marine fishes allied to pipefishes in the family Syngnathidae......
shad
shad, any of several saltwater food fishes of the herring family (Clupeidae) that swim up rivers to spawn. Shad......
shark
shark, any of numerous species of cartilaginous fishes of predatory habit that constitute the order Selachii (class......
sheepshead
sheepshead, (Archosargus probatocephalus), popular edible sport fish in the family Sparidae (order Perciformes),......
shrimpfish
shrimpfish, any of four species of small, tropical marine fishes of the family Centriscidae (order Gasterosteiformes),......
Siamese fighting fish
Siamese fighting fish, (Betta splendens), freshwater tropical fish of the family Osphronemidae (order Perciformes),......
silversides
silversides, any of several species of small slim schooling fish of the family Atherinidae (order Atheriniformes),......
skate
skate, (order Rajiformes), in zoology, any of numerous flat-bodied cartilaginous fishes constituting the order......
sleeper
sleeper, any of the marine and freshwater fishes of the family Eleotridae of the suborder Gobioidei (order Perciformes).......
slickhead
slickhead, any of several deep-sea fishes, family Alepocephalidae (order Salmoniformes), found in almost all oceans......
slipmouth
slipmouth, any of certain fishes (order Perciformes) that are characterized by slimy bodies with small scales and......
smelt
smelt, any of certain silvery, chiefly marine food fishes, family Osmeridae, closely related to salmon and trout......
snail darter
snail darter, Rare species (Percina tanasi) of darter that originally was found only in the Little Tennessee River......
snailfish
snailfish, any of about 115 species of marine fish often placed with the lumpsuckers in the family Cyclopteridae,......
snake eel
snake eel, any of numerous marine fishes in the family Ophichthidae (order Anguilliformes). Representatives of......
snakehead
snakehead, any of a number of species of freshwater fish of the family Channidae, found in Africa and Asia. Snakeheads,......
snapper
snapper, any of about 105 species of fishes of the family Lutjanidae (order Perciformes). Snappers are found, often......
snipefish
snipefish, any of about 18 species of marine fishes of the family Centriscidae (order Gasterosteiformes) found......
snook
snook, any of about eight species of marine fishes constituting the genus Centropomus and the family Centropomidae......
soapfish
soapfish, any of about 24 species of marine fishes constituting the tribe Grammistini (family Serranidae; order......
sockeye salmon
sockeye salmon, (Oncorhynchus nerka), North Pacific food fish of the family Salmonidae that lacks distinct spots......
sole
sole, any of a variety of flatfishes, but, more strictly, those of the family Soleidae (order Pleuronectiformes).......
soupfin shark
soupfin shark, (Galeorhinus galeus), shark species of the family Triakidae inhabiting temperate and subtropical......
spadefish
spadefish, (family Ephippidae), any of about 17 species of marine fishes (order Perciformes), predominantly tropical......
spearfish
spearfish, any of certain marine fishes of the genus Tetrapterus, family Istiophoridae (order Perciformes). Spearfishes......
spiny eel
spiny eel, any of two groups of fishes, those of the freshwater family Mastacembelidae (order Perciformes) and......
spiny shark
spiny shark, any of a group of more than 150 species of small extinct fishes traditionally classified in the class......
spiny-finned fish
spiny-finned fish, any member of the superorder Acanthopterygii, including four orders of marine and freshwater......
spookfish
spookfish, any of about 11 species of small marine fishes constituting the family Opisthoproctidae (order Salmoniformes),......
squawfish
squawfish, any of several edible fishes of the genus Ptychocheilus found in the rivers of western North America.......
squirrelfish
squirrelfish, any of about 70 species of large-eyed, colourful, tropical reef fish of the family Holocentridae......
stargazer
stargazer, fish of two related families, Uranoscopidae (electric stargazers) and Dactyloscopidae (sand stargazers),......
stickleback
stickleback, any of about eight species of fishes in five genera of the family Gasterosteidae (order Gasterosteiformes)......
stingray
stingray, any of a number of flat-bodied rays noted for the long, sharp spines on their tails. They are sometimes......
stonefish
stonefish, (Synanceia), any of certain species of venomous marine fish of the genus Synanceia and the family Synanceiidae,......
sturgeon
sturgeon, (family Acipenseridae), any of about 29 species of fishes of the family Acipenseridae (subclass Chondrostei),......
sucker
sucker, (family Catostomidae), any of the freshwater fishes constituting the family Catostomidae, similar to and......
sunfish
sunfish, any of numerous species of North American freshwater fishes placed with the crappies and black basses......
surfperch
surfperch, any of 23 species of fishes of the family Embiotocidae (order Perciformes). Surfperches are found in......
surgeonfish
surgeonfish, any of about 75 species of thin, deep-bodied, tropical marine fishes of the family Acanthuridae (order......
swamp eel
swamp eel, any of about 15 species of slim, eel-like fish comprising the order Synbranchiformes. Swamp eels, unrelated......
sweeper
sweeper, any of the fishes of the genera Parapriacanthus or Pempheris, in the family Pempheridae (order Perciformes),......
sweetfish
sweetfish, delicately flavoured marine fish that migrates upstream to spawn in clear waters. It is found in East......
swim bladder
swim bladder, buoyancy organ possessed by most bony fish. The swim bladder is located in the body cavity and is......
swordfish
swordfish, (Xiphias gladius), prized food and game fish, probably the single species constituting the family Xiphiidae......
swordtail
swordtail, (Xiphophorus hellerii), popular tropical fish of the live-bearer family Poeciliidae (order Atheriniformes).......
tarpon
tarpon, any of certain marine fish of the family Megalopidae (order Elopiformes), related to the bonefish and the......
teleost
teleost, (infraclass Teleostei), any member of a large and extremely diverse group of ray-finned fishes. Along......
tench
tench, (Tinca tinca), widely distributed Eurasian aquarium and game fish of the carp family Cyprinidae (order Cypriniformes),......
tetra
tetra, any of numerous attractively coloured freshwater fishes of the characin family, Characidae, often kept in......
tetraodontiform
tetraodontiform, (order Tetradontiformes), any member of a group of primarily tropical marine fishes that are closely......
The 1916 Shark Attacks That Gave Sharks a Bad Rap
These days, even the mention of sharks can strike fear into the hearts of many—but it wasn’t always this way. Decades......
threadfin
threadfin, any of about 41 species of marine fishes of the family Polynemidae (order Perciformes), widely distributed......
thresher shark
thresher shark, (genus Alopias), any of three species of sharks of the family Alopiidae noted for their long, scythelike......
tiger shark
tiger shark, (Galeocerdo cuvier), large, potentially dangerous shark of the family Carcharhinidae. It is noted......
tigerfish
tigerfish, any of several fishes so named on the basis of their pugnacity when caught, their fiercely predaceous......
tilapia
tilapia, common name used for certain species of fishes belonging to the family Cichlidae (order Perciformes),......
tilefish
tilefish, any of about 40 species of elongated marine fishes in the family Malacanthidae (order Perciformes), with......
toadfish
toadfish, any of about 80 species of bottom-living fishes constituting the family Batrachoididae and the order......
Today in History—July 2: The Canadian Cod Fishery Collapse
On this day in 1992, the Canadian government confirmed what thousands of people in Newfoundland and Labrador already......
tonguefish
tonguefish, any of the small marine flatfishes of the family Cynoglossidae, found in the tropics, especially in......
triggerfish
triggerfish, any of about 30 species of shallow-water marine fishes of the family Balistidae, found worldwide in......
tripletail
tripletail, any of four species of fishes constituting the family Lobotidae (order Perciformes). The family contains......
tropical fish
tropical fish, Any of various small fishes of tropical origin often kept in aquariums. They are interesting for......
trout
trout, any of several prized game and food fishes of the family Salmonidae (order Salmoniformes) that are usually......