Fish

Fish are the most diverse group of vertebrates, with well over 34,000 species. They breathe through gills, move with fins, and occupy nearly every aquatic habitat — from Himalayan streams to the crushing dark of ocean trenches. Sharks and rays belong here too, in the cartilaginous branch.

19 guides in this group

Fish LC Anglerfish Melanocetus johnsonii The deep-sea anglerfish lures prey with a glowing rod on its head in water with no sunlight, and the tiny male fuses permanently to the huge female, becoming a living sperm supply. Read the guide →

Fish LC Atlantic Bluefin Tuna Thunnus thynnus The Atlantic bluefin tuna is a warm-blooded ocean sprinter that can weigh 700 kg, cross the Atlantic in weeks, and sell for over a million dollars a fish — which nearly wiped it out. Read the guide →

Fish LC Atlantic Mudskipper Periophthalmus barbarus The Atlantic mudskipper is a fish that spends most of its life out of water, walking on its fins across mudflats, breathing through its skin and mouth, and defending a burrow it digs with its jaws. Read the guide →

Fish LC Blue Tang Paracanthurus hepatus The blue tang is the electric-blue reef fish made famous as Dory. It plays dead when threatened, carries a scalpel-sharp blade at the base of its tail, and is one of the hardest marine fish to breed. Read the guide →

Fish VU Bull Shark Carcharhinus leucas The bull shark is the shark that swims up rivers — hundreds or thousands of kilometres into fresh water. Learn how it survives there, why it's rated among the most dangerous sharks, and its status. Read the guide →

Fish LC Clownfish Amphiprion ocellaris The clownfish lives inside the stinging tentacles of a sea anemone, protected by a special mucus coat. Every clownfish is born male, and the largest in each group turns female. Read the guide →

Fish CR Coelacanth Latimeria chalumnae The coelacanth is a metre-and-a-half deep-sea fish thought extinct for 66 million years until one was caught in 1938. Its lobed, limb-like fins link it to the ancestors of all land vertebrates. Read the guide →

Fish LC Electric Eel Electrophorus electricus The electric eel is not an eel but a knifefish that generates up to 860 volts — the strongest electric discharge of any animal. Learn how it stuns prey, breathes air, and leaps to shock threats. Read the guide →

Fish LC Great Barracuda Sphyraena barracuda The great barracuda is a torpedo-shaped reef predator with fang-like teeth that strikes at up to 40 km/h. It is curious about swimmers but rarely bites, and its flesh can carry ciguatera poisoning. Read the guide →

Fish CR Great Hammerhead Shark Sphyrna mokarran The great hammerhead is the largest hammerhead shark, using its wing-shaped head to detect and pin stingrays on the seabed. Once common, it is now Critically Endangered from the fin trade. Read the guide →

Fish LC Green Moray Eel Gymnothorax funebris The green moray is a large Atlantic reef eel that is actually brown — a yellow mucus coat makes it look green. It has a second set of jaws in its throat that lunge forward to grab prey. Read the guide →

Fish EN Manta Ray Mobula birostris The manta ray is the largest ray in the sea — a 7-metre, plankton-eating fish with the biggest brain of any fish and a curiosity about divers. Learn how it feeds, breeds, and why it is Endangered. Read the guide →

Fish VU Ocean Sunfish Mola mola The ocean sunfish is the heaviest bony fish in the world, a flattened disc with no tail that can weigh over two tonnes, basks on its side at the surface, and lays more eggs than any other vertebrate. Read the guide →

Fish LC Red Lionfish Pterois volitans The red lionfish is a striped Indo-Pacific reef fish armed with venomous spines. Released into the Atlantic by the aquarium trade, it has become one of the most damaging marine invasions on record. Read the guide →

Fish LC Red-Bellied Piranha Pygocentrus nattereri The red-bellied piranha is a South American river fish with interlocking razor teeth and a fearsome reputation that outruns the facts. It shoals for safety, scavenges widely, and rarely bites people. Read the guide →

Fish VU Seahorse Hippocampus kuda The seahorse is a fish that swims upright, grips seagrass with a monkey-like tail, and in which the male carries the pregnancy. Learn how this slow, armoured ambush hunter lives. Read the guide →

Fish NT Tiger Shark Galeocerdo cuvier The tiger shark eats almost anything — turtles, seabirds, dolphins, other sharks, and the occasional car tyre. Learn how its serrated teeth and roaming lifestyle make it a key ocean predator. Read the guide →

Fish EN Whale Shark Rhincodon typus The whale shark is the largest fish in the sea — a 12-metre, spotted filter feeder that strains plankton and is completely harmless to people. Learn how it feeds, breeds, and why it's Endangered. Read the guide →

Fish VU Great White Shark Carcharodon carcharias The great white is the largest predatory fish alive. Learn how it senses prey, why it breaches, how slowly it reproduces, and what its Vulnerable status really means. Read the guide →