Koi stand for perseverance, good fortune and love. Here is what each koi color means, the story behind the yin yang koi, and how these fish moved from Chinese legend to Japanese ponds.
Most fish cannot blink because they have no eyelids, so they sleep with their eyes open. Here is which fish can cover their eyes, how fish see underwater and how to tell when your fish is asleep.
Fish are not mammals. They breathe with gills, run cold and lay eggs, while whales and dolphins breathe air, keep warm and nurse their calves. Here is how to tell the two apart.
Nearly every fish has teeth, from a goldfish’s hidden throat teeth to a great white’s conveyor belt of blades. Here is where fish teeth sit, how they work and which pets can bite.
Fish diets range from algae and plankton to insects, crabs and other fish. Here is what pet, pond and wild fish eat, how often to feed them and what to keep out of the tank.
Unicornfish are horned relatives of the tangs found on Indo-Pacific reefs. Learn what the horn is for, how to identify the main Naso species, where they live and whether one belongs in your aquarium.
Walking fish use fins, fin rays and even gill covers to move over land or along the seafloor. Meet 13 walking fish, learn how they breathe air and see which ones are legal to keep.
Meet 15 of the rarest fish in the world, from the Devils Hole pupfish to the coelacanth. See each species’ IUCN status, range, threats and what the law says about keeping rare fish.
A complete clownfish care guide covering ocellaris, percula and maroon species, tank setup, water parameters, anemones, pairing, diseases and typical US costs.
Which puffers truly live in fresh water, and how to keep them: nine species compared, tank setup, a snail-based diet, beak trimming, tank mates, toxicity and common diseases.