Koi Quarantine Protocols: Salt Treatment, KHV Testing, and Isolation Duration

Quarantine is the most important disease prevention practice in koi keeping. Every fish introduced without quarantine is a potential source of pathogens that can devastate a collection built over years and at significant expense. The protocols are straightforward, but they require discipline and dedicated infrastructure.

Quarantine Setup

A proper quarantine system is a completely separate pond, tank, or container with its own filtration, aeration, and equipment. Water from the quarantine system should never flow into your main pond. Use separate nets, buckets, and maintenance tools for quarantine fish and do not share them with your main system. A simple 500 to 1000 gallon above-ground pond or circular tank is sufficient for most hobby operations.

Salt Treatment

Salt (sodium chloride, non-iodized) is the standard first treatment for all new koi arrivals. Salt at 0.3 percent (3 kg per 1000 liters or 2.5 lbs per 100 gallons) provides a mild antiparasitic effect, reduces osmotic stress, and stimulates mucus coat regeneration. Maintain this concentration for the first two weeks of quarantine. Dissolved salt does not evaporate, so only add replacement salt for water changes, not top-offs. At 0.5 percent salt, treatment efficacy against gill flukes and some external protozoa increases.

KHV Testing

Koi Herpesvirus testing is recommended for any high-value fish joining a collection and for any fish sourced from a location where KHV exposure is uncertain. PCR testing from a swab or gill biopsy can identify KHV carrier status. The temperature window for KHV active replication is 60 to 77 degrees F (16 to 26 C), which is also the temperature at which quarantine is typically conducted in spring and fall. If KHV is suspected during quarantine, contact your state fish health authority.

Isolation Duration

Minimum quarantine duration for koi is 3 to 4 weeks at temperatures between 64 and 72 degrees F (18 to 22 C). At colder temperatures, incubation periods extend and a 6-week quarantine is more appropriate. During the entire period, observe fish daily, test water every other day, and document any symptoms or treatments. Fish that complete quarantine with a clean bill of health, healthy appetite, and no parasites or lesions can be integrated into the main pond.