Koi fish do have teeth, but their dental structure is completely different from that of humans, with the following unique characteristics:
Location and Name of the Teeth
Koi teeth are called "pharyngeal teeth" and grow in the throat area (pharynx), as part of the lower pharyngeal bone. This structure is common among cyprinid fish (such as goldfish and grass goldfish).
Shape and Arrangement
They are arranged in a "V" shape, symmetrically on both sides, with 5 teeth on each side, totaling 10.
They are divided into main teeth (3 in row A) and auxiliary teeth (1 each in rows B and C). The main teeth have larger crowns and are closely arranged, responsible for most of the chewing function.
Their shape can vary due to environmental differences, appearing flat, finger-like, or hooked.
Tooth Replacement
Koi regularly shed and replace their pharyngeal teeth. The shed teeth often appear as small white 颗粒 (about the size of a grain of rice, with a groove on one side) at the bottom of the tank or on the filter cotton.
Functions and Limitations
Pharyngeal teeth can cut or crush food but cannot directly bite hard objects (like some aquatic plants) the way mammalian teeth do.
In traditional Chinese medicine, they are called "carp teeth" and are believed to have diuretic and (relieving urinary tract blockages) effects.
It’s important to note that koi have no teeth on their lip edges and rely solely on pharyngeal teeth for chewing. If you find small white at the bottom of the tank during breeding, they are most likely normally shed pharyngeal teeth, so there’s no need to worry excessively.