Just like humans, Betta fish sleep at night. "When sleeping, they become still, with their eyes open because of their absence of eyelids. Betta fish may lose their color while sleeping (it's their ...

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 protective mucous cocoon surrounds this parrotfish as it sleeps in Australia's Great Barrier Reef. This layer of protection helps fend off predators so parrotfish can get a good night's rest.

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 ...

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 ...

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 ...