* Kingfish (_Menticirrhus saxatilis_) is a small, silvery fish found in the coastal waters of the western Atlantic Ocean. It is a popular food fish and is also used for bait.
* Kitefin shark (_Dalatias licha_) is a small, deep-sea shark found in all oceans except the Arctic. It is a slow-moving fish that feeds on small fish and squid.
* Knifefish (_Gymnotiformes_) are a group of freshwater fish found in South America. They have long, slender bodies and are known for their ability to generate electricity.