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Actinopterygii & Chondrichthyes · Fins & gills

Fish

Fish are aquatic vertebrates with gills and fins for all or most of life — from reef clownfish to great white sharks. This is WARN's fish section: 36 sourced species guides plus 4 type pages covering sharks & rays, reef fish, freshwater fish and deep-sea fish.

36 species guides 4 types 13 threatened species covered
Search all 36 guides Browse by type
Sharks
Cartilaginous skeletons — not bone
Whale shark
Largest living fish; a filter feeder
Fresh water
Tiny share of water; outsized share of fish diversity
Deep sea
Bioluminescent lures and pressure-adapted bodies

Types

The everyday groupings people search for. Each type has its own page with identification pointers, FAQs and the matching species guides.

All 36 guides

Search by name, or filter by type, conservation status, region and letter.

Showing 1-24 of 36 animals

Animal group
A silver freshwater angelfish with tall fins and dark vertical bars swimming among green aquarium plants.
Domesticated aquarium fish; wild type widespread in the Amazon basin

Reef fish

A

Angelfish

Pterophyllum scalare (Lichtenstein, 1823) — freshwater angelfish, family Cichlidae

Tall, graceful Amazon cichlids — community-tank icons bred into many colour and fin varieties.

South America — Amazon basin (wild type); aquariums worldwide

Open guide
Dark deep-sea anglerfish with a glowing lure and large toothy mouth
Least Concern

Deep-sea fish

A

Anglerfish

Lophiiformes

The deep-sea hunter with a glowing lure

Oceans

Open guide
Banded archerfish with silver flank bands swimming just below the surface in a mangrove estuary
Least Concern

Reef fish

A

Archerfish

Toxotes jaculatrix (Pallas, 1767) — family Toxotidae

A fish that shoots insects off leaves with a jet of water — and corrects for refraction.

Indo-Pacific mangroves and estuaries · From India to northern Australia and Melanesia

Open guide
Atlantic cod with barbel on chin over sandy seabed
Vulnerable

Other

A

Atlantic Cod

Gadus morhua

The fish that built Atlantic nations

Europe · North America

Open guide
Basking shark with enormous open mouth filter-feeding near the surface
Endangered

Sharks & rays

B

Basking Shark

Cetorhinus maximus (Gunnerus, 1765) — family Cetorhinidae

The second-largest fish on Earth, filtering an Olympic pool of water every couple of hours.

Temperate coastal waters worldwide · Summer surface feeding off Britain, Ireland and the north-east Atlantic

Open guide
A male Betta splendens with flowing red and blue fins displayed in a heated, planted aquarium — not a flower vase.
Vulnerable

Freshwater fish

B

Betta

Betta splendens (Regan, 1910)

The labyrinth fish of rice paddies — wild Vulnerable, pet trade flooded with fighting-fish myths.

Thailand · Cambodia

Open guide
Living blobfish as a firm deep-sea fish on the ocean floor, not a decompressed specimen
Not Evaluated

Deep-sea fish

B

Blobfish

Psychrolutes marcidus (McCulloch, 1926) — family Psychrolutidae

The famous photograph is not what a blobfish looks like. It is what one looks like after being killed.

Deep waters off south-eastern Australia and Tasmania · New Zealand

Open guide
Bright royal blue tang fish with a yellow tail swimming over a coral reef
Least Concern

Reef fish

B

Blue Tang

Paracanthurus hepatus

The bright blue reef fish from Finding Nemo

Oceans

Open guide
Stocky grey bull shark swimming through murky coastal water near the seabed
Vulnerable

Sharks & rays

B

Bull Shark

Carcharhinus leucas

The shark that swims into freshwater

Oceans

Open guide
Channel catfish with barbels near river bottom
Least Concern

Freshwater fish

C

Channel Catfish

Ictalurus punctatus

North America's whiskered bottom feeder

North America

Open guide
An ocellaris clownfish with bright orange body and three white bands nestled among the tentacles of a host sea anemone on a coral reef.
Least Concern

Reef fish

C

Clownfish

Amphiprion ocellaris (Cuvier, 1830)

Anemone dwellers of the reef — beloved in aquaria, bound to vanishing coral.

Indo-Pacific — Andaman Sea to western Pacific; introduced to Caribbean in aquaria

Open guide
A European eel with a serpentine body and small pectoral fins gliding through clear freshwater over gravel and weed.
Critically Endangered

Freshwater fish

E

Eel

Anguilla anguilla (Linnaeus, 1758)

A serpent of rivers and mystery — Critically Endangered after decades of decline.

Europe · North Africa

Open guide
Long dark electric eel swimming through murky freshwater near submerged plants
Least Concern

Freshwater fish

E

Electric Eel

Electrophorus electricus

The fish that generates powerful electric shocks

South America

Open guide
A vivid red-orange common goldfish (Carassius auratus) with flowing white-tipped fins swimming in dark water among other goldfish.
Domesticated

Freshwater fish

G

Goldfish

Carassius auratus (Linnaeus, 1758)

Centuries of selective breeding — not a bowl fish, and never for release into wild waterways.

Worldwide — domestic and feral; native to East Asia

Open guide
Great white shark swimming in clear blue ocean water, showing its grey back, white underside, and powerful body
Vulnerable

Sharks & rays

G

Great White Shark

Carcharodon carcharias

The ocean's most famous apex predator

Oceans

Open guide
A male guppy with iridescent blue tail and orange body swimming among live plants in a planted freshwater aquarium.
Least Concern

Freshwater fish

G

Guppy

Poecilia reticulata (Peters, 1859)

The beginner's tropical fish that science knows best — Least Concern in the wild, mistreated in cups.

Trinidad and Tobago · Venezuela

Open guide
Hammerhead shark with its distinctive wide flat head swimming in blue water
Critically Endangered

Sharks & rays

H

Hammerhead Shark

Sphyrnidae

The shark with a head like a hammer

Oceans

Open guide
A red-and-white Kohaku koi gliding beneath the surface of a clear garden pond with aquatic plants along the edges.
Wild common carp Vulnerable in native range; koi are domestic ornamental lines

Freshwater fish

K

Koi

Cyprinus carpio haematopterus — ornamental domestic carp (Cyprinus carpio)

Living jewels of the pond — centuries of Japanese artistry on a Vulnerable wild carp.

Worldwide — ornamental ponds; wild carp native to Europe and Asia

Open guide
Largemouth bass with open mouth near lily pads
Least Concern

Freshwater fish

L

Largemouth Bass

Micropterus salmoides

America's favourite freshwater game fish

Africa · Asia

Open guide
Red lionfish with bold reddish-brown stripes and fanlike venomous spines hovering over Atlantic reef rubble where it is an invasive species
Least Concern in native range

Reef fish

L

Lionfish

Genus Pterois — red lionfish P. volitans and devil firefish P. miles invasive in the Atlantic

A spectacular Indo-Pacific predator that became the textbook Atlantic invasive — venomous, fertile and unchecked.

Native: Indo-Pacific coral reefs · Invasive: Western Atlantic, Caribbean and Gulf of Mexico since the 1980s

Open guide
A giant manta ray gliding through blue water with wide triangular pectoral fins and cephalic lobes extended.
Endangered

Sharks & rays

M

Manta Ray

Mobula birostris (giant) and Mobula alfredi (reef manta)

Ocean giants with wingspans rivalling small aircraft — filter-feeders under serious threat.

Tropical and subtropical oceans worldwide — coasts, reefs and open water

Open guide
A blue marlin with cobalt-blue flanks, spear-like bill and towering dorsal fin cutting through tropical open ocean swells.
Vulnerable

Other

M

Marlin

Makaira nigricans (Lacepède, 1802)

Billfish giants of the tropics — Vulnerable to longlines, sport fishing and bycatch.

Tropical and subtropical oceans worldwide — Atlantic, Pacific and Indian

Open guide
Mudskipper with bulging eyes and mottled brown skin perched on a mangrove mudflat at low tide
Not Evaluated for most species

Reef fish

M

Mudskipper

Periophthalmus spp. — family Oxudercidae (formerly Gobiidae)

A fish that walks on land, breathes through its skin and spends more time out of water than in it.

Indo-Pacific mangrove mudflats · Tropical west Africa for some species

Open guide
Ocean sunfish drifting upright in open blue ocean
Vulnerable

Other

O

Ocean Sunfish

Mola mola (Linnaeus, 1758) — family Molidae

A fish that looks like a head with fins, grows 60 million times its birth weight, and basks on its side.

Temperate and tropical oceans worldwide · Open ocean, often near the surface

Open guide

Quick answers

Browse all answers →

Fishing pressure and habitat loss decide most fish futures

Industrial fishing, dams, reef bleaching and the ornamental trade remove fish faster than slow-growing sharks and specialised reef species can replace themselves.

Free, sourced guides exist so readers can replace myths with mechanisms — and so every page can still route toward habitat and rescue funding when someone is ready to act.

Fund aquatic protection Start with sharks & rays

Fish: frequently asked questions

What belongs in this section?
WARN groups everyday types people search for, then lists every matching species guide. Use the type pages for identification; use the A–Z browse for the full set.
How are types different from taxonomy?
Types are everyday groupings — snakes, reef fish, insects — not formal Linnaean ranks. They cut across orders when that matches how people look things up.
Does every guide appear in a type?
Most do. Guides that do not fit a type cleanly still appear in the full A–Z browse on this hub.
Are the facts sourced?
Yes. Species guides carry IUCN status, citations and FAQs. Type pages summarise identification and conservation patterns for the group.
How can I help threatened species in this group?
Support habitat protection, avoid wildlife products linked to illegal trade, and use free sourced guides to replace myths that obscure real threats.
Where else should I look?
Animals A–Z lists every guide on the site. The glossary explains Red List categories. Appeals and donate pages fund partner-led rescue.

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