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.

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 ...

Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to curiouskidsus@theconversation.com. Could you explain how fish sleep? Do they drift ...

Do fish with no eyelids sleep? Given that they spend their entire lives submerged in water, this is a reasonable question to ask. Do fish with no eyelids sleep? Given that they spend their entire ...

Tom has a Master's degree in Journalism. His editorial work covers anything from archaeology and the environment to technology and culture. Tom has a Master's degree in Journalism. His editorial work ...

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 ...