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National Koi Day: A Fishy Exam

Categories: Animals, Veterinary Exam

Happy National Koi Day!

The Sacramento Zoo’s veterinary team provides excellent care and treatment for all of the animals at the zoo, from Kamau the lion to the smallest lizard. Even the koi fish receive top-notch care. And, just like the other animals at the zoo, the koi are given annual preventative exams to make sure they stay in good health.

Koi, known as nishikigoi in Japan, are a type of ornamental Amur carp. Amur carp were cultured as a food fish throughout East Asia. Breeders began selectively breeding carp for their colors in the 1820’s in the Niigata Prefecture in Japan, which gave rise to koi fish. The many varieties of koi were introduced to the world in 1914 in an annual exhibition in Tokyo. From there, breeders quickly took to the species, crossbreeding and cultivating more flashy varieties. Today, there are 82 different varieties of koi recognized by the All Japan Nishikoi Promotion Association.

Koi being examined at the vet hospital

To care for our fish, the veterinary team first gently net all nine fish out of their pond and put them in large, water-filled tubs to transport them back to the veterinary hospital. Once at the hospital, the fish are transferred into tubs containing a mixture of pond water and anesthetic powder, which reduces the stress on the fish and keeps them from wiggling during their exams. Veterinary staff keep a close eye on each fish and monitor their vitals to ensure the safety of the animals while under anesthesia.

Throughout the examination, water is gently pumped into the fish’s mouth and gills to maintain oxygen and anesthetic flow. When the fish are transferred from station to station, staff use plastic bags, allowing them to be as gentle as possible and protect the fishes’ delicate, protective coat of slime.

two vets examine a koiA blood draw and small skin scrape sample is collected and sent for analysis, looking for signs of parasites and disease. After that, a radiograph and ultrasound allow veterinarians to look at the koi’s internal organs. If any abnormalities are found, the medical team will explore further to see if the fish is suffering from any abscesses, tumors, or build-ups.

Once the exam is complete, the fish are transferred to “recovery tubs” filled with pond water. There, the koi slowly wake up from the anesthetic under the watchful eye of the veterinary team. Once the staff is satisfied that the fish are fully awake and given a clean bill of health, they are returned to their home in the sensory garden area of the zoo.

On your next visit to the Sacramento Zoo, take a moment to sit in the sensory garden across from cheetah brothers, Rowdy and Zig Zag. Take a moment to breathe, reflect, and enjoy the nishikigoi swimming peacefully in the pond before you.


On this National Koi Day, here are some fun koi facts:

  • Koi can live more than 200 years, though most live between 30-40 years in human care. The oldest koi fish on record was named Hanako. She hatched in 1751 and lived to be 226 years old!
  • Koi fish are susceptible to sunburn, so their ponds need shade and deep water.
  • Given the right conditions, koi can grow up to three feet long.