Fish
Gill-bearing aquatic vertebrates maneuvering with specialized fins and tracking water flow with lateral lines.
European Eel
A river fish thought to spawn only in the Sargasso Sea, after a 5,000 to 10,000 km migration, though its spawning has never been observed.
Fangtooth
The bathypelagic hunter reported to have the largest teeth of any marine fish for its head size, fangs so long an adult cannot fully close its mouth.
Frilled Shark
A slow-swimming, six-gilled deep-sea shark whose lineage is estimated at 82 million years old and whose pregnancy may run three and a half years.
Giant Freshwater Stingray
The 300-kilogram Mekong river phantom with a barbed tail spine and the record for the largest freshwater fish ever caught and officially recorded.
Giant Oarfish
A silver ribbon reliably documented to 8 meters, with a red dorsal fin along its whole length, seen swimming upright in the open ocean.
Giant Oceanic Manta Ray
The ocean's largest ray has three pairs of fins, a wingspan of up to 26 feet, and can dive past 1,000 metres.
Great Barracuda
A long, tube-shaped hunter with two sets of razor-sharp teeth that chops big fish in half.
Great Torpedo Ray
170-to-220-volt shocks from a honeycomb of barely visible electric organs, and jaws that stretch to swallow surprisingly big fish.
Green Humphead Parrotfish
The biggest herbivorous fish on coral reefs, whose males settle rivalries with headbutts.
Green Moray Eel
The reef predator that lies in wait in rock crevices, wearing a thick yellow mucus that turns its dark skin green and protects it from parasites and disease.
Gulper Eel (Pelican Eel)
A huge gape, a mouth that first unfolds and then inflates, and a glowing tail tip.
Humpback Anglerfish
The female wears a lure on her snout and can swallow a fish longer than herself.
Koi
A pet carp bred into over 100 colour varieties that, in one study, sought out a human hand.
Leafy Seadragon
Seaweed-like flaps, transparent oscillating fins, and a sway like plants in the current.
Mahi-Mahi
A gold-and-blue ocean sprinter that can pass 4 feet long in its first year.
Nile Tilapia
A mouth-brooding cichlid; in one lab strain, a Y-chromosome gene proved essential for maleness.
Northern Pike
A freshwater ambush predator that lies cocked in an S, then strikes with a sprint.
Ocean Sunfish (Mola Mola)
Up to 1.3 tonnes of cartilage-and-jelly fish with no tail fin. It dives for siphonophores, then floats flat at the surface between dives.
Ocellaris Clownfish
A reef fish about 8 cm long that shelters among stinging anemone tentacles, where the breeding male turns female if the female is lost.
Rainbow Trout
A stream fish whose sex is set by a Y-chromosome gene unrelated to any known sex-differentiating gene.
Red Lionfish
Swims at half its prey's speed and still wins six lab chases in ten.
Red-Bellied Piranha
Razor-sharp interlocking teeth, a red belly, and a school that doubles as cover from predators.
Red-Lipped Batfish
A Galápagos batfish whose genus walks the seabed on modified fins.
Sea Lamprey
A jawless survivor from a lineage that split from ours roughly 500 million years ago, armed with a sucker mouth ringed in rasping teeth.