Fish: Different Types, Definitions, Photos, and More

Updated: January 3, 2023
© Arif Supriyadi/Shutterstock.com
Share this post on:

©A-Z-Animals.com

Fish are aquatic vertebrates. They usually have gills, paired fins, a long body covered with scales, and tend to be cold-blooded.

“Fish” is a term used to refer to lampreys, sharks, coelacanths, and ray-finned fishes, but is not a taxonomic group, which is a clade or group containing a common ancestor and all its descendants.

Instead, there are 3 main classes, groups, or types of fish: bony fish (Osteichthyes), jawless fish (Agnatha), and cartilaginous fish (Chondrichthyes). Fish are the most diverse group among vertebrates, with over 33,000 different types of fish species.

No one really knows how many different types of fish exist in the world, more are being discovered constantly. We may soon have over 35,000, or even 40,000 known species!

5 Fish Characteristics

Cubera Snapper
There are three superclasses into which fish are grouped: Bony fish, jawless, and cartilaginous fish.

©Lynn Archer/Shutterstock.com

There are three superclasses into which fish are grouped: Bony fish (Osteichthyes), jawless fish (Agnatha), and cartilaginous fish (Chondrichthyes). Ray-finned fishes are of the class Actinopterygii, while lobe-finned fishes are of the class Sarcopterygii. Both are clades of bony fishes.

Regardless, all fish have some characteristics in common that distinguish them from other animals.

  • Cold-bloodedness: All fish are ectothermic or cold-blooded, meaning they cannot regulate their internal body temperature. Even warm-blooded fish such as tuna and mackerel sharks have only “regional endothermy” or warm-bloodedness limited to certain areas.
  • Water habitat: All fish live in bodies of water, whether it is freshwater or saltwater. However, not all creatures that live in water are fish.
  • Gills to breathe: Fish have gills throughout their life cycle. As with the water habitat, although all fish have gills, not all creatures with gills are fish.
  • Swim bladders: Specialized organs fill with air to keep the fish afloat and in some species help them survive with low oxygen levels. They also help fish sleep and are sensitive enough to detect the movement of food and predators.
  • Fins for movement: Most common are a tail fin, a pair of side fins, a dorsal fin, and an anal fin. Variations exist but they all provide motion, maneuverability, and stability.

For a list of incredible facts about fish, make sure to read ‘10 Incredible Fish Facts.’

Diet

Fish eat crustaceans, plants, shrimp, and worms.

What do fish eat? Most species of fish fall into the omnivore category. This means that they can eat both plants and meat. It offers a wider range of food options for aquatic animals. It also helps fish find the different nutrition they need in a variety of foods.

Additionally, pet fish may have a bit of a different diet than fish you find in the wild. For example, pet fish mostly eat freeze-dried and frozen foods including bloodworms, brine shrimp, krill, and plankton.

Evolution and Origins

Oilfish
Oilfish contain high levels of wax esters, which are indigestible to humans.

©Porco_Rosso/Shutterstock.com

Fish have been evolving and changing for a very, very long time. Fish began to evolve during the Cambrian explosion approximately 530 million years ago. The earliest chordates formed skulls and spinal columns, which helped to evolve craniates and vertebrates. Additionally, the earliest fish lineages were the Agnatha or the jawless fish.

Early fish from fossil records are represented by a group of small armored and jawless fish. These were known as ostracoderm. These jawless fish lineages are mostly extinct now. However, an extant clade, the lampreys may have pre-dated the ancient pre-jawed fish. The first jaws were found in fossils and they lacked any teeth.

The diversity of these jawed creatures may prove the evolutionary advantages of a jawed mouth. Although interesting, it remains unclear if there was ever an advantage of a hinged jaw.

Furthermore, fish may have evolved from a creature similar to a coral sea squirt whose larva resembled primitive fish in very important ways.

Exceptions

Animals That Have Multiple Hearts: Hagfish
Hagfish are the only animals that have a skull but no vertebral column.

©Frank Fennema/Shutterstock.com

There are several exceptions to the common definition of a fish. For example, hagfish don’t have scales and aren’t true vertebrates (or are considered primitive vertebrates); mudskippers are amphibious fish that can live outside water; lungfish use lungs instead of gills to breathe; lampreys lack paired fins, and tuna are warm-blooded.

Also, not all fish groups come from fish lineages. The superclass Tetrapoda of the four-listed animals is considered to be a group within Sarcopterygii and includes amphibians, reptiles, birds, and mammals. Hence, Sarcopterygii includes both lobe-finned fishes and tetrapods.

Finally, not all aquatic creatures which resemble fish are considered fish. Whales, dolphins, and porpoises are aquatic mammals, for example.

You can read about some types of fish that are extinct.

Pregnancy

A Siamese female fighting fish guarding her newly laid eggs amongst the bubble nest.
A Siamese female fighting fish guarding her newly laid eggs amongst the bubble nest.

©mnoor/Shutterstock.com

  • There are two main types of fish pregnancies, ovoviviparity or aplacental viviparity (egg-bearing) and viviparous (embryo-bearing). Both are considered to be live-bearing.
  • Ovoviparity has the eggs develop and hatch internally, with the young being born alive. It can express either ovuliparity (external fertilization of eggs and zygote development), oviparity (internal fertilization of eggs and external development of zygotes as eggs with yolks), or ovoviviparity (internal fertilization of eggs and internal development of embryos with yolks). Stingrays, seahorses, and some shark species are ovoviviparous. So are guppies, mollies, swordtails, halfbeaks and platies.
  • Viviparity has embryos develop internally before being born live. It can express either histotrophic (“tissue-eating”) viviparity (mother provides no nutrition and embryos eat their unborn siblings or mother’s unfertilized eggs) or hemotrophic (“blood-eating) viviparity (mother provides nutrition, usually through a placenta). Many shark species are viviparous.

Check out the fish gestation period.

Different Types of Fish:

A Alaskan Pollock
Alaskan Pollock

It's one of the most commonly eaten fish in the world

A Albacore Tuna
Albacore Tuna

The albacore is a very fast swimmer

A Alligator Gar
Alligator Gar

The alligator gar has toxic eggs to protect against predators

A Amano Shrimp
Amano Shrimp

Popular kept in aquariums to keep them clean

A American Eel
American Eel

Don't eat raw eel! Their blood is poisonous to humans when consumed raw.

A Anchovies
Anchovies

November 12th is celebrated as National Pizza with the Works Except Anchovies Day

A Angelfish
Angelfish

There are 70 different species!

A Anglerfish
Anglerfish

The anglerfish has a glowing lure on its head to attract unsuspecting prey

A Arapaima
Arapaima

One of the largest freshwater fish

A Archerfish
Archerfish

Archerfish can shoot a stream of water up to five feet with amazing accuracy.

A Arctic Char
Arctic Char

Arctic char is the northern-most fish; no other fish lives anywhere further north!

A Asian Arowana
Asian Arowana

The male Asian arowana raises the eggs in its mouth

A Asian Carp
Asian Carp

Asian carp can consume 40% of their body weight in food a day!

A Atlantic Salmon
Atlantic Salmon

These fish are known for their ability to leap and fight when hooked.

A Atlantic Sturgeon
Atlantic Sturgeon

Atlantic Sturgeon often leap out of the water.

A Australian Flathead Perch
Australian Flathead Perch

This small fish fetches a high price tag, with individuals selling from $1,000 to $5,000.

A Baiji
Baiji

Baijis use echolocation to find food in the Yangtze River.

A Banana Eel
Banana Eel

Named for the yellow body and brown spots that make it look like a banana.

A Banjo Catfish
Banjo Catfish

The banjo catfish is extremely shy and known for hiding from onlookers.

A Barb
Barb

There are over 1768 known species!

A Barracuda
Barracuda

Can grow to nearly 2 meters long!

A Barramundi Fish
Barramundi Fish

Scale rings indicate age

A Barreleye Fish (Barrel Eye)
Barreleye Fish (Barrel Eye)

A barreleye fish's eyes can rotate in their head to look for prey.

A Bass
Bass

Prized by sport fishers for their size and strength

A Batfish
Batfish

The batfish has a lure on its head to attract prey

A Beluga Sturgeon
Beluga Sturgeon

The beluga sturgeon is one of the largest bony fish in the world!

A Betta Fish (Siamese Fighting Fish)
Betta Fish (Siamese Fighting Fish)

Can live in low-oxygen environments!

A Bigfin Reef Squid 
Bigfin Reef Squid 

Can change color through use of chromatophores

A Black Marlin
Black Marlin

Every black marlin is born as a female.

A Blacknose Shark
Blacknose Shark

When threatened, Blacknose sharks raise their head, arch their back, and lower their pectoral fins.

A Bladefin Basslet
Bladefin Basslet

The tiny bladefin basslet belongs to the same subfamily as the giant grouper, Epinephelinae.

A Blobfish
Blobfish

One of the ugliest creatures in existence!

A Blue Catfish
Blue Catfish

It's a strong fighter when caught on a fishing line

A Blue Eyed Pleco
Blue Eyed Pleco

Can live safely with many types of fish.

A Blue Shark
Blue Shark

Blue sharks can have up to 135 pups at a time.

A Bluefin Tuna
Bluefin Tuna

The bluefin is one of the largest fish in the world

A Bluegill
Bluegill

The world record for longest bluegill is 15 inches.

A Bonito Fish
Bonito Fish

May eat squid or other small invertebrate ocean life

A Bonnethead Shark
Bonnethead Shark

Bonnetheads are the only hammerhead sharks that use their pectoral fins to swim.

A Bowfin
Bowfin

The bowfin is a primitive fish that first evolved in the Jurassic

A Boxfish
Boxfish

Can release a toxin from its skin

A Bronze Whaler Shark
Bronze Whaler Shark

The Bronze Whaler Sharks only hunt in large groups.

A Brook Trout
Brook Trout

The Brook Trout is actually part of the salmon family, making it not technically a trout.

A Buffalo Fish
Buffalo Fish

The oldest Buffalo fish recorded was 112 years old!

A Bull Trout
Bull Trout

The bull trout is not actually a trout, but a member of the char family.

A Butterfly Fish
Butterfly Fish

There are more than 100 different species!

A Carp
Carp

The carp is one of the most popular pond fishes in the world

A Catfish
Catfish

There are nearly 3,000 different species!

A Chimaera
Chimaera

Also called ghost shark

A Chinese Paddlefish
Chinese Paddlefish

The Chinese paddlefish is one the largest freshwater fish in the world

A Chinook Salmon
Chinook Salmon

The Chinook salmon undertakes a long migration for the spawning season

A Cichlid
Cichlid

There are more than 2 000 known species!

A Clearnose Skate
Clearnose Skate

The skate with translucent nose patches

A Clownfish
Clownfish

Also known as the anemonefish!

A Cobia Fish
Cobia Fish

It has teeth not only in its jaws but in its tongue and the roof of its mouth

A Codfish
Codfish

They eat other fish

A Coelacanth
Coelacanth

The coelacanth first evolved almost 400 million years ago.

A Conger Eel
Conger Eel

The European Conger ( Conger conger) can weigh as much as an adult human!

A Cookiecutter Shark
Cookiecutter Shark

The cookiecutter shark takes its name because it leaves a cookie-shaped bite hole in its prey.

A Cory Catfish
Cory Catfish

All Cory Catfish have three pairs of barbels around their mouth that they use to detect food.

A Crappie Fish
Crappie Fish

The crappie is one of the most popular freshwater fish in North America.

A Cubera Snapper
Cubera Snapper

While very intimidating, the cubera snapper also falls prey to other marine animals like barracudas, whale sharks, and moray eels.

A Danios
Danios

These fish make a popular choice for aquarium hobbyists due to their hardy nature.

A Discus
Discus

One of the only schooling Cichlids!

A Dragon Eel
Dragon Eel

Dragon eels have double jaws and two sets of razor-sharp teeth

A Dragonfish
Dragonfish

Dragonfish can emit red light from their eyes

A Drum Fish
Drum Fish

The drum fish makes a croaking sound with its swimming bladder!

A Dusky Shark
Dusky Shark

The Dusky Shark sometimes eats trash discarded by humans.

A Eagle Ray
Eagle Ray

Majestic underwater bird like fish

A Eel
Eel

Eels can be a mere few inches long to 13 feet!

A Eel catfish
Eel catfish

Eel catfish breathe air and reach up on land to catch beetles. Scientists think they may be a missing link between fish and lizards.

A Electric Catfish
Electric Catfish

The electric catfish can discharge an electric shock up to 450 volts

A Electric Eel
Electric Eel

Despite its powerful shock, electric eels have terrible vision.

A Elephant Fish
Elephant Fish

Elephant fish are known as the Australian ghost shark, but they are not actually a shark species!

A Ember Tetra
Ember Tetra

Ember tetras are one of the smallest shoaling fish in the world

A Emperor Angelfish
Emperor Angelfish

One of the most beautiful fish on the planet!

A Escolar
Escolar

Its system can’t metabolize wax esters, which can lead to unpleasantness for diners.

A Fangtooth
Fangtooth

Has the largest teeth compared to body size of any known fish

A Fire Eel
Fire Eel

Fire Eels are not true eels.

A Fish
Fish

Respire through the gills on their heads!

A Flathead Catfish
Flathead Catfish

The only predators that prey on flathead catfish are members of their own species and humans who catch them for commercial and recreational purposes.

A Florida Gar
Florida Gar

The Florida gar has toxic eggs to protect against predators

A Flounder
Flounder

A flat fish found in the Atlantic and Pacific!

A Flounder Fish
Flounder Fish

There are around 240 different species of Flounder fish

A Flowerhorn Fish
Flowerhorn Fish

The Flowerhorn fish is an artificial species; it does not exist naturally

A Fluke Fish (summer flounder)
Fluke Fish (summer flounder)

The chameleon of the seas!

A Flying Fish
Flying Fish

Can glide in the air for hundreds of feet

A Football Fish
Football Fish

The football fish is named after its unusual round or oblong shape

A Freshwater Drum
Freshwater Drum

These fish are very vocal, and males make a rumbling or grunting noise during breeding season to attract a mate.

A Freshwater Eel
Freshwater Eel

Freshwater eels are actually catadromous, meaning they migrate to saltwater to spawn

A Freshwater Jellyfish
Freshwater Jellyfish

The freshwater jellyfish is native to China but is now found all over the world

A Freshwater Sunfish
Freshwater Sunfish

Four species of the freshwater catfish have gone extinct

A Frilled Shark
Frilled Shark

Frilled Sharks got their name from the six rows of gills on their throat that look like ruffled collars.

A Frogfish
Frogfish

The frogfish can change colors, but it takes several weeks to do so

A Galapagos Shark
Galapagos Shark

Galapagos sharks are cannibalistic and sometimes eat their young, so the pups stay away from the adults in shallow water.

A Gar
Gar

Can grow to more than 3m long!

A Garden Eel
Garden Eel

Garden eel colonies are made up of hundreds to thousands of individuals.

A Ghost Catfish
Ghost Catfish

You can see its heart beating

A Giant Trevally
Giant Trevally

The largest fish in its genus

A Goblin Shark
Goblin Shark

Goblin Sharks are called a living fossil because their family, Mitsukurinidae, can be traced back 125 million years.

A Goby Fish
Goby Fish

Some Goby species are toxic.

A Goldfish
Goldfish

Goldfish and common carp can mate and produce offspring

A Goliath Tigerfish
Goliath Tigerfish

Featured in River Monsters TV series

A Goonch Catfish
Goonch Catfish

The goonch catfish, or giant devil catfish, is one of the most fierce freshwater fish.

A Gourami
Gourami

Gourami fishes show parental care for their young

A Grass Carp
Grass Carp

The grass carp is considered to be a natural weed control agent.

A Great Hammerhead Shark
Great Hammerhead Shark

Great hammerhead sharks have a 360 view because their eyes are situated on the ends of their mallet-like heads.

A Great White Shark
Great White Shark

Can grow to more than 8 meters long!

A Green Sunfish
Green Sunfish

Juvenile Green Sunfish are less colorful than their parents because they need to blend in with their surroundings to avoid predators.

A Greenland Shark
Greenland Shark

This shark has the longest lifespan of any vertebrate.

A Grey Reef Shark
Grey Reef Shark

One of the most common shark species!

A Gulper Catfish 
Gulper Catfish 

Gulper catfish can consume prey twice its size

A Gulper Eel 
Gulper Eel 

Gulper eels have a similar lifespan to humans and can live up to 85 years old. However, their age depends on their habitat and the availability of food.

A Guppy
Guppy

Also known as the Millionfish!

A Haddock
Haddock

The haddock is very popular in both recreational and commercial fishing

A Hagfish
Hagfish

Can use slime to suffocate marine predators or escape capture

A Haikouichthys
Haikouichthys

Haikouichthys was the first animal to develop a well-defined head

A Hairy Frogfish
Hairy Frogfish

Hairy frogfish can eat prey as large as themselves by swallowing them whole.

A Halibut
Halibut

The word "halibut" is comes from haly meaning "holy" and butte meaning flat fish due to its popularity on Catholic holy days.

A Hammerhead Shark
Hammerhead Shark

Found in coastal waters around the world!

A Hardhead Catfish
Hardhead Catfish

The hardhead catfish has a sharp spine near its fin to inject venom

A Herring
Herring

People enjoy the taste of the oily fish in many different ways including pickled, smoked, salted, dried and fermented.

A Horn Shark
Horn Shark

Endemic to the Californian coast!

A Horse Mackerel
Horse Mackerel

Got their name from a myth that other fish would ride them over great distances

A Immortal Jellyfish
Immortal Jellyfish

Excellent hitchhiker on long-trip cargo ships

A Irukandji Jellyfish
Irukandji Jellyfish

Tiny ocean killer

A Jellyfish
Jellyfish

Have tentacles around their mouths!

A John Dory
John Dory

The John Dory is often labeled one of the ugliest fish in the world and has no known relatives.

A Kelp Greenling
Kelp Greenling

Male Kelp Greenlings participate in an unusual mating ritual by fertilizing eggs in the nests of other males.

A Keta Salmon
Keta Salmon

During spawning the look of the male changes. Among other things, he grows a beak called a kype that bears fangs.

A Keyhole Cichlid
Keyhole Cichlid

When these fish feel stressed, their skin color will change from yellow-cream to brown.

A Killifish
Killifish

Killifish are highly sought after for their peaceful nature and ability to adapt to most aquarium communities.

A King Salmon
King Salmon

Largest of the Pacific salmon

A Kissing Gourami
Kissing Gourami

The kissing gesture that the kissing gourami displays is not a mating gesture

A Knifefish
Knifefish

Produce weak electric fields

A Koi Fish
Koi Fish

In Japanese, the word koi sounds like the word for love. So the fish is a symbol of love among other good things.

A Kokanee Salmon
Kokanee Salmon

A non-anadromous type of sockeye salmon

A Krill
Krill

The krill is perhaps the most important animal in the marine ecosystem!

A Labout’s Fairy Wrasse
Labout’s Fairy Wrasse

Females are sequential hermaphrodites, which means they can convert to males anytime during their life cycle.

A Lake Sturgeon
Lake Sturgeon

Its skeleton is part cartilage and part bone.

A Lamprey
Lamprey

Not related to the eel

A Lancetfish
Lancetfish

Lancetfish live at depths up to 6,500 feet below sea level

A Lawnmower Blenny
Lawnmower Blenny

Must be in temperatures of 78 degrees Fahrenheit to breed

A Leopard Shark
Leopard Shark

Leopard Sharks have teeth with three points.

A Leptocephalus
Leptocephalus

Leptocephali have flat bodies filled with jelly-like substances, surrounded by a thin layer of muscle.

A Lionfish
Lionfish

Females can release up to 15,000 eggs at a time!

A Lizardfish
Lizardfish

The lizardfish can camouflage itself against the sandy bottom to avoid predators.

A Loach
Loach

Have sharp spines below their eyes

A Longnose Gar
Longnose Gar

The longnose gar species of the gar family has potentially existed for 100 million years.

A Lumpfish
Lumpfish

The lumpfish have sticky suction cups on their fins

A Lungfish
Lungfish

The lungfish first evolved almost 400 million years ago.

A Mahi Mahi (Dolphin Fish)
Mahi Mahi (Dolphin Fish)

It's called the rabbit of the ocean because it multiplies so quickly.

A Manta Ray
Manta Ray

Can grow up to 9m wide!

A Masked Angelfish
Masked Angelfish

All masked angelfish are female until sometime after sexual maturity, at which point some become male.

A Megalodon
Megalodon

The largest shark to ever live!

A Megamouth Shark
Megamouth Shark

Swims with its mouth open to capture prey

A Mekong Giant Catfish
Mekong Giant Catfish

The Mekong giant catfish is the largest purely freshwater fish in the world

A Milkfish
Milkfish

Females lay up to 5 million eggs at one time in warm, shallow and salty waters

A Mojarra
Mojarra

The mojarra's protruding mouth allows it to sift along the seabed for food

A Mola mola (Ocean Sunfish)
Mola mola (Ocean Sunfish)

The ocean sunfish is the biggest bony fish in the world

A Molly
Molly

Known for their calm and peaceful nature!

A Monkfish
Monkfish

Called "The Poor Man's Lobster!"

A Moon Jellyfish
Moon Jellyfish

Moon Jellies are bioluminescent, so they glow in the dark! They can also de-age!

A Moray Eel
Moray Eel

Sometimes, groupers invite moray eels to help them hunt!

A Mullet Fish
Mullet Fish

The Striped Mullet is one of the best-known and most easily identified species, with black horizontal stripes along its body.

A Needlefish
Needlefish

no stomach to digest food

A Neon Tetra
Neon Tetra

Neon Tetras are very social and peaceful fish.

A Neptune Grouper
Neptune Grouper

The largest recorded specimen ever caught was 17" long

A Nurse Shark
Nurse Shark

Commonly found in Central American waters!

A Oarfish
Oarfish

The Giant oarfish (Regalecus glesne) holds the Guinness Book of World Records for the longest bony fish in the world.

A Ocean Whitefish
Ocean Whitefish

Common around Southern California

A Oilfish
Oilfish

They live in deep water as far as 2,600 feet below the water’s surface.

A Opah
Opah

Opah are brightly colored, with red-orange fins and a silvery body.

A Opaleye (Rudderfish)
Opaleye (Rudderfish)

Some indigenous people of the Pacific coast of North America consider opaleye fish sacred food and use it in traditional ceremonies.

A Orange Roughy 
Orange Roughy 

One of the oldest commercially harvested fish

A Orchid Dottyback
Orchid Dottyback

This fish camouflages as its prey's parents to trick it into becoming dinner.

A Oscar Fish
Oscar Fish

The Oscar fish has teeth in its throat!

A Oyster Toadfish
Oyster Toadfish

The oyster toadfish can produce poison to protect itself

A Ozark Bass
Ozark Bass

Ozark Bass only live in Arkansas and Missouri

A Pacific Sleeper Shark
Pacific Sleeper Shark

In 2015, a Pacific Sleeper Shark was filmed living underneath an active volcano near the Solomon Islands. This shark is able to survive in waters with very high temperatures and acidity!

A Paddlefish
Paddlefish

Paddlefish have existed since the Cretaceous Period

A Parrotfish
Parrotfish

The parrotfish can change from female to male at some point in its life.

A Peacock Bass
Peacock Bass

Peacock bass is known for their aggressive behavior and predatory instincts, making them a challenging target for sport fishermen.

A Peppermint Angelfish
Peppermint Angelfish

The peppermint angelfish was only first described in 1992.

A Perch Fish
Perch Fish

Some of the most delicious gamefish in the world

A Pictus Catfish
Pictus Catfish

Pictus catfish are social fish that should be kept in groups of 4 or more

A Pike Fish
Pike Fish

Apex freshwater predators with fearsome teeth!

A Pink Salmon
Pink Salmon

The smallest of the North American salmon

A Pipefish
Pipefish

The male pipefish has the ability to carry fertilized eggs with him

A Piranha
Piranha

Generally found in fast-flowing streams!

A Platinum Arowana
Platinum Arowana

The male broods the eggs and baby fish in his mouth.

A Pollock Fish
Pollock Fish

Pollock is a nutritious fish, generally readily available for human consumption, and more sustainable and affordable than other whitefish species like hake or haddock.

A Porbeagle Shark
Porbeagle Shark

The porbeagle is one of the few sharks that jumps out of the water

A Pufferfish
Pufferfish

The second most poisonous creature in the world!

A Pygmy Shark
Pygmy Shark

Pygmy sharks underbelly glows to attract prey that swims beneath it.

A Pyjama Shark
Pyjama Shark

Pyjama Sharks like to swim in shallow inshore waters.

A Rainbow Kribs (Kribensis)
Rainbow Kribs (Kribensis)

Rainbow Kribs sometimes nip the fins of other fish, especially ones with long, flowing tails, which is too tempting for them not to bite.

A Rainbow Shark
Rainbow Shark

The rainbow shark has been genetically modified to glow in the dark

A Red Drum Fish
Red Drum Fish

There were a few sightings of red drums in the Mediterranean Sea off Sicily and Israel, but they do not naturally occur there, so theories are they escaped from fish farms.

A Red-Lipped Batfish
Red-Lipped Batfish

Despite its weird looks, the red-lipped batfish is harmless to humans

A Redhump Eartheater
Redhump Eartheater

The redhump eartheater are very passive fish and do well in aquariums with non-cichlid species

A Redtail Catfish
Redtail Catfish

One of three giant catfish species

A Reef Shark
Reef Shark

Grey reef sharks can give birth without males

A Rockfish
Rockfish

These fish can grow up to three feet long!

A Sailfish
Sailfish

Fast billfish with a sail-like dorsal fin

A Salmon
Salmon

Returns upstream every year to spawn

A Salmon Shark
Salmon Shark

Salmon sharks are related to Great Whites.

A Sand Tiger Shark
Sand Tiger Shark

The sand tiger is the shark most commonly seen in aquariums.

A Sardines
Sardines

Schools of sardines can be miles long and are often visible from an airplane

A Sawfish
Sawfish

Sawfish teeth keep growing as the fish gets older

A Scorpion Fish
Scorpion Fish

There are more than 200 recognised species!

A Sculpin
Sculpin

Its skull bones can compress so the fish can fit in narrow spaces

A Sea Dragon
Sea Dragon

Inhabits tropical coastal waters of Australia!

A Sea Slug
Sea Slug

All sea slugs have both male and female sex organs

A Sea Urchin
Sea Urchin

Can live for up to 200 years!

A Seahorse
Seahorse

Males give birth to up to 1,000 offspring!

A Shark
Shark

No shark species has any bones in their bodies

A Sheepshead Fish
Sheepshead Fish

This fish has teeth that resemble a human's.

A Shortfin Mako Shark
Shortfin Mako Shark

Shortfin Mako sharks can jump 20 feet above the water!”

A Silky Shark
Silky Shark

Has an extremely acute sense of hearing

A Silver Dollar
Silver Dollar

Closely related to the Piranha

A Sixgill shark
Sixgill shark

The sixgill shark has six pairs of gills instead of the normal five

A Skate Fish
Skate Fish

More than 200 species exist!

A Skipjack Tuna
Skipjack Tuna

The skipjack is the most commonly caught tuna in the world

A Sleeper Shark
Sleeper Shark

The Greenland shark is one of the longest living vertebrates in the world.

A Smallmouth Bass
Smallmouth Bass

A fierce fighter!

A Smooth Hammerhead Shark
Smooth Hammerhead Shark

Congregate in large groups during annual migrations

A Snailfish
Snailfish

The deepest ocean-dweller is a snailfish who was found over 26,700 feet below sea level.

A Snook Fish
Snook Fish

Males change into females after the spawning season

A Snowflake Eel
Snowflake Eel

Snowflake Eel have two jaws to help them swallow their food.

A Sockeye Salmon
Sockeye Salmon

Called "red salmon" because their skin turns bright red to dirty red during spawning season

A Speckled Trout
Speckled Trout

Speckled trout are not actually a species of trout.

A Spinner Shark
Spinner Shark

Can have up to 20 babies

A Spiny Dogfish
Spiny Dogfish

Found in ocean waters worldwide!

A Sponge
Sponge

There are more than 9,000 known species!

A Spotted Gar
Spotted Gar

They are commonly mistaken as logs in the water due to their cylindrical body.

A Spotted Garden Eel
Spotted Garden Eel

Males battle each other over females and territory

A Squirrelfish
Squirrelfish

Uses vibrations to communicate with other fish

A Starfish
Starfish

Has 2 stomachs to aid digestion!

A Stargazer Fish
Stargazer Fish

Uses an electric shock to stun its prey!

A Steelhead Salmon
Steelhead Salmon

Steelhead live in freshwater rivers and streams for 1 to 2 years before migrating into the ocean

A Stingray
Stingray

It's stinger is razor-sharp or serrated!

A Stonefish
Stonefish

The most venomous fish in the world

A Stoplight Loosejaw
Stoplight Loosejaw

Emit red light to hunt via bioluminescent photophores

A Sturgeon
Sturgeon

Large species can swallow whole salmon

A Sucker Fish
Sucker Fish

Commonly found throughout America!

A Surgeonfish
Surgeonfish

Paracanthurus hepatus, the palette surgeonfish or bluetang, is the only member of its genus

A Swai Fish
Swai Fish

The edges of an iridescent shark's fins have a signature glow

A Swordfish
Swordfish

Lose their scales and teeth as adults

A Tang
Tang

Found around shallow coral reefs!

A Tarpon
Tarpon

Its genus dates back to the Cretaceous period – 113 million years ago

A Telescope Fish
Telescope Fish

Swallows food, much of it larger than them, whole

A Tetra
Tetra

Native to the freshwater streams of South America!

A Thornback Ray
Thornback Ray

The skate with the biggest spines!

A Thresher Shark
Thresher Shark

Thresher Sharks have a distinctive, thresher-like tail.

A Tiger Muskellunge (Muskie)
Tiger Muskellunge (Muskie)

Massive carnivorous hybrid fish

A Tiger Trout
Tiger Trout

As tiger trout are sterile, they cannot produce offspring. However, they do have relatively long lifespans and can live up to 10 years in captivity.

A Tire Track Eel
Tire Track Eel

They like to burrow into aquarium sand.

A Toadfish
Toadfish

Can be heard out of water

A Triggerfish
Triggerfish

There are 40 species of Triggerfish, all with different coloring and patterns.

A Trout
Trout

They don’t have scales for their first month of life!

A Tuna
Tuna

The tuna has a sleek body that enables it to swim quickly through the water

A Uaru Cichlid
Uaru Cichlid

The color of the Uaru cichlid changes during the spawning season

A Urechis unicinctus (Penis Fish)
Urechis unicinctus (Penis Fish)

Create "inns" for other sea creatures

A Viper Shark (dogfish)
Viper Shark (dogfish)

Most data on these fish is based on observations near Japan.

A Viperfish
Viperfish

Viperfish have a bioluminescent spine on their dorsal fin.

A Wahoo Fish
Wahoo Fish

Wahoo can change colors when they're excited and while they hunt

A Walking Catfish
Walking Catfish

The walking catfish can move on land while breathing air

A Walleye Fish
Walleye Fish

Has great night vision

A Wels Catfish
Wels Catfish

The wels catfish is among the largest freshwater fish in the world.

A Whale Shark
Whale Shark

The largest species of fish in the world!

A White Catfish
White Catfish

White catfish can grow up to 37 inches in size.

A White Crappie
White Crappie

Common freshwater fish in North America

A White Sturgeon 
White Sturgeon 

They don't have any teeth!

A Whiting
Whiting

"Whiting" can refer to certain other species of ray-finned fish

A Wolf Eel
Wolf Eel

Wolf Eels may become tame and interact with human in areas where people frequently dive.

A Wolffish
Wolffish

The wolffish has impressive canines with a powerful bite force!

A Wrasse
Wrasse

There are more than 500 different species!

A Wrought Iron Butterflyfish
Wrought Iron Butterflyfish

Is endemic to Japan.

A Xingu River Ray
Xingu River Ray

The Xingu River ray is only found in the Xingu River in Brazil.

A Xiphactinus
Xiphactinus

Xiphactinus was the largest bony fish of the Cretaceous Period.

A Yellow Bullhead Catfish
Yellow Bullhead Catfish

Bottom dwelling scavenger fish

A Yellow Perch
Yellow Perch

Female Yellow Perch grom larger than the males.

A Yellowfin Tuna
Yellowfin Tuna

The yellowfin forms schools with other tuna species

A Yellowtail Snapper
Yellowtail Snapper

Fast moving ocean fish with a long yellow stripe.

A Zebra Pleco
Zebra Pleco

The zebra pleco is a bottom feeder with a sucker mouth.

A Zebra Shark
Zebra Shark

Can get to be 30 years old in the wild!

List of Fish

Share this post on:
About the Author

My name is Rebecca and I've been a Professional Freelancer for almost a decade. I write SEO content and graphic design. When I'm not working, I'm obsessing over cats and pet rats.

Fish: Different Types, Definitions, Photos, and More FAQs (Frequently Asked Questions) 

What are the 3 types of fish?

Bony fish, jawless fish and cartilaginous fish.

What's the most famous fish?

The most famous fish is the coelacanth, which has four lobed fins resembling limbs. It is one of the world’s most ancient fish species. Its name means “hollow spine” and comes from the Greek words koilos (hollow) and akantha (spine).
Coelacanth also refers to the order Coelacanthiformes. which comes from the clade Sarcopterygii and subclass Actinistia. It includes two species in the genus Latimeria: the West Indian Ocean coelacanth (Latimeria chalumnae) and the Indonesian coelacanth (Latimeria menadoensis).

Can fish feel pain?

Yes, fish can feel pain, but it is different from the expression of pain from humans. It is difficult to test fish for pain except by looking for unusual behavior and physiological responses in reaction to certain stimuli.

What do fish eat?

Fish can be predatory, foraging or filter-feeding. Their diets can be carnivorous or omnivorous depending on the species and can include prey from zooplankton to invertebrates, crustaceans, annelids and smaller fish.

Discover a fish with human-like teeth here!

How do fish breathe?

Fish usually breathe through gills, which filters oxygen through water. However, some fish breathe using different means. Lungfish have lungs and mudskippers can breathe through wet skin and the lining of their mouth and throat.

What are the smallest and largest fish?

The smallest fish is the cyprinid fish (8mm) and the largest fish is the whale shark (12m).

What is the difference between "fish" and "fishes"?

“Fish” refers to the singular and one species or to the plural within context. “Fishes” refers to the plural, especially when talking about more than one species of fish.

What are the main differences between the flying fox fish and the Siamese algae eater?

The main differences between the flying fox fish and the Siamese algae eater are color, length and shape, mouth shape, and algae preferences.

Thank you for reading! Have some feedback for us? Contact the AZ Animals editorial team.