River
Streamlined bodies and strong pectoral fins adapted to fight river currents and navigate shifting silt channels.
American Paddlefish
An ancient river giant that carries 50,000 to 70,000 electroreceptor organs, the largest number of any living vertebrate species.
Atlantic Salmon
Hatches in a river, grows up in the ocean, and finds its way home by the chemistry of its birth stream.
Barramundi
A fish that mostly matures as a male and switches to female as it grows, on its way to a maximum length of 200 cm.
Beluga Sturgeon
A giant sturgeon that mostly hunts open-water fish and now survives largely through hatcheries.
Channel Catfish
A catfish called a swimming tongue, with taste buds all over its body to find food in murky water.
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.
Goliath Frog
The largest frog in the world, where males haul rocks to build nests for their eggs.
Nile Crocodile
An armored crocodile whose skin is more touch-sensitive than a primate's fingertips.
Rainbow Trout
A stream fish whose sex is set by a Y-chromosome gene unrelated to any known sex-differentiating gene.
Red-Bellied Piranha
Razor-sharp interlocking teeth, a red belly, and a school that doubles as cover from predators.
Signal Crayfish
A plague-resistant crayfish brought to Europe to supplement stocks the plague decimated, and a carrier of the disease itself.
Sockeye Salmon
A silver sea-going fish that turns bright red and swims back to the freshwater system where it hatched.