* Dorsal Fin: A single fin located on the back.
* Anal Fin: A single fin located on the underside of the body, near the tail.
* Caudal Fin: This is the tail fin, and is the largest fin.
* Pectoral Fins: These are the paired fins located just behind the gills.
While there are four main fins, some Koi breeds may have additional, smaller fins, called ventral fins, located on the belly.