You’re staring at your aquarium. It’s late. Everything is quiet. And there’s your fish, floating calmly, fins moving slowly, eyes wide open. Are they... asleep? Or just zoning out? Fish don’t come ...

A large group of yellowfin tuna swimming off the coast of Italy. Like all fish, they sleep, but it's not like human sleep. Giordano Cipriani/The Image Bank via Getty Images From the goldfish in your ...

Sleep in fish may look different from humans, but rest is essential for survival. Here’s what experts have to say about fish sleep. A protective mucous cocoon surrounds this parrotfish as it sleeps in ...

Choose the Right Tank Size A fish can never be happy when it has restricted space to move. Most individuals have fish in bowls or extremely small tanks, which restrict swimming space and oxygen ...

Betta, or Siamese fighting, fish are among "the most popular freshwater aquarium fish in the world," PetMD reports. Native to southeast Asia, this species is known for its range of vibrant hues. There ...

Betta, or Siamese fighting fish, are one of the most popular aquarium fish in the world. Originating from southeast Asia, betta fish are known for their diverse range of colors with over 70 different ...

A large group of yellowfin tuna swimming off the coast of Italy. Like all fish, they sleep, but it’s not like human sleep. Giordano Cipriani/The Image Bank via Getty Images Michael Heithaus, Florida ...