Fish

A fish is a water-dwelling animal with a backbone, gills for breathing, and no limbs with fingers or toes. This category includes living creatures like hagfish, lampreys, cartilaginous, bony fish, and some extinct relatives. The majority of it, about 95%, belong to the ray-finned group, specifically the Actinopterygii class. Among these, nearly 99% are teleosts.

It’s plentiful in most bodies of water, adapting to various aquatic environments, from high mountain streams to the deepest ocean depths like the abyssal and hadal zones, where creatures like cusk-eels and snailfish thrive. Interestingly, no fish species have been confirmed to exist in the deepest 25% of the ocean. It exhibit remarkable species diversity, boasting 34,300 known species, surpassing all other vertebrate groups in this regard.