Koi fish may nibble on objects such as rocks, plants, or even their owners’ hands, but this behaviour is usually harmless and not perceived as a form of aggression. This brings us to a question, do koi fish have teeth?

All koi varieties don’t have traditional teeth like other animals with jaws. Instead, they have pharyngeal teeth located at the back of their throat. These specialized teeth-like structures help the fish grind up and break down food.

This does away with the fear of being bitten by your koi fish since the teeth are far back in the mouth that hand-feeding them like I do poses no risk of harm. I talk more about it below.

Koi fish pharyngeal teeth

Do koi fish have teeth?

Koi fish have specialized teeth-like structures known as pharyngeal teeth. These teeth are attached to the upper and lower pharyngeal jaws in their throat, just after the gill chambers. 

Koi fish use the pharyngeal teeth to chew, crush, and grind food in a repeated chewing motion, which can sometimes be heard when you listen carefully. The fish can also rub its teeth-like structures together to produce sounds and communicate with each other. 

These sets of teeth are mostly functional during feeding time. Besides, koi fish are peaceful and won’t use their teeth to bite each other. Therefore, you can hand-feed the fish without fear of a bite.

With this type of teeth, they’re not very good at chewing food and may swallow it whole. As such, if you place guppies in their tank to eat algae, for example, they might swallow the smaller guppies whole.

Note that koi fish teeth are quite different from human teeth. Their teeth are bony projections that grow on the pharyngeal arch, pointing inward and upwards. Thus not visible from the outside of the fish’s body.

Do koi fish shed their teeth?

Are you always worried when you find some teeth in your filter or at the bottom of your koi’s pond? Don’t worry because that’s normal. There are three rows of teeth in koi, and it is healthy that they shed their teeth.

Koi fish can shed thirty or more sets of teeth in their lifetime. You will see koi fish shaking vigorously at the bottom of the pond or aquarium like it’s biting or fighting prey. The teeth-shedding is usually succeeded by 2-3 days of not eating.

However, a koi fish that has shed its pharyngeal teeth sometimes feeds on soft food.

The teeth-shedding process does not happen at regular intervals. Whenever the old set of teeth stops functioning well, Koi will shed them off to allow for a new set of teeth. That occurs mostly during Spring.

Signs of koi fish shedding teeth

Here are some signs that a koi fish is shedding its teeth:

  • Shaking: You might notice your koi fish shaking or “convulsing” at the bottom of the pond. You would think your fish is fighting prey.
  • 2-3 days without eating: Koi fish can go for 2-3 days without eating when they are in the teeth-shedding process. That’s because they cannot bite with loose and painful pharyngeal jaws.
  • White teeth-like pellets at the bottom of the pond: When you have crystal clear koi pond water, you will notice white teeth-like pellets at the bottom.
  • Bony structures in your pond filter: When cleaning your pond, you may find some tiny bony structures clogging the filter system.

Always clean the filter if you have many koi fish in your pond. Otherwise, the teeth will block your filters and create a harmful environment for the fish. While there are fish that may not need a filter, koi need a filter to also clean their ponds in general.

Do koi fish bite?

Koi fish are docile and will not bite you when feeding them. Besides, koi fish teeth are located far back in their throat, making it even more difficult for the fish to bite you. 

However, koi fish have strong mouth muscles. They might pull your finger into their mouth while sucking food. Due to the location of their teeth, you will not feel any bite. In the case of a bite, it is usually a painless one.

Additionally, koi fish taste their food before pushing them back into their throat for chewing. Your finger is not part of a Koi’s meal. Therefore, it will push it out rather than send it back for chewing. On very rare or close to no occasions will Koi fish bite anyone.

Final Thought

Finger-feeding your koi fish will create a good relationship between you and your fish. Therefore, take your time to feed your koi to satisfaction. If you do that, the fish will always come to greet you whenever it sees you heading towards the pond or fish tank.

Koi fish also don’t bite other fish because they are not hunters. The fish can only be aggressive during their mating season. Therefore ensure they always have enough space in the pond or tank and the right diet to avoid aggression.

Also, find out: Do koi fish sleep?


  • Cover, S. (2003). Koi Anatomy.
  • Pharyngeal teeth, Wikipedia.

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