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Quarantine

By the koi.wiki editorial team · Updated

Key facts: Quarantine is the practice of isolating newly acquired koi from an established population for a period of time to observe for signs of disease before introduction, widely cited as the most dependable method of preventing pathogen introduction into a pond.[1][2]
Quarantine in koi keeping refers to housing new fish in a physically separate system, away from a resident pond, so that illness can be detected and managed before the new arrivals are mixed with existing stock.[3][2] The University of Florida IFAS Extension describes quarantine as the most dependable method to avoid introducing pathogens into a pond or facility, and recommends a minimum of 30 days, with koi herpesvirus (KHV) quarantine specifically done at 75°F (24°C) for at least 30 days.[1]The word “quarantine” derives from a historical 40-day isolation period used for ships during plague outbreaks, though modern aquaculture usage sets duration according to the pathogens of concern rather than a fixed historical figure.[8]

Why quarantine new koi

Newly purchased koi may carry parasites, bacteria, fungi, or viruses without visible signs, and transport stress can cause latent infections to become active.[5][9] According to UF/IFAS, handling and transport reduce disease resistance, and recovery from this stress may take weeks.[2] Quarantine protects an established population from exposure to pathogens the new fish may be shedding, while also giving the new fish time to recover from shipping stress and acclimate to new water, feed, and management before full exposure to the resident population's pathogens.[3]Sources vary in their recommended minimum length. UF/IFAS recommends a minimum 30-day quarantine for general fish health management and specifically for KHV risk.[1][9] The World Organisation for Animal Health (WOAH) states that for KHV biosecurity, new fish should be held with sentinel fish at permissive temperatures for a minimum of 4 weeks to 2 months before transfer to the main site.[4] The Southern Regional Aquaculture Center notes that quarantine length depends on the diseases of concern, species, and intended use of the animals, with an ideal quarantine period of 30 to 60 days suggested for future broodstock.[10] UF/IFAS Extension's recirculating systems guidance gives a broader range of 1 to 8 weeks depending on species, disease concerns, system, and prior testing.[3]According to the US importer Kodama Koi Farm, observation periods of 14–21 days are commonly described in hobbyist guidance, though the farm also states that it extends its own commercial quarantine to 30 days specifically to catch KHV outbreaks, noting that in its experience KHV typically breaks out within two weeks in Hawaii's climate.[5][11]

Temperature and KHV risk

Koi herpesvirus disease (KHV) outbreaks typically occur in spring and autumn when water temperatures are between 60°F and 77°F (16°C and 25°C), with an incubation period of 7–21 days depending on temperature.[1] Warmer temperatures induce clinical disease more rapidly than lower temperatures; the virus can infect fish without causing signs at around 55°F (13°C), but disease can emerge later when temperatures return to a permissive range.[1] For this reason, UF/IFAS recommends that koi intended for KHV quarantine be held at 75°F (24°C) for at least 30 days to provoke and detect disease if present.[1] Kodama Koi Farm similarly advises maintaining quarantine water above 70°F, stating that koi immune systems function best at this temperature and that KHV requires warm water to appear.[5] See also the dedicated page on koi herpesvirus (KHV).

Setting up a quarantine system

Observation, sampling and testing

Fish in quarantine should be observed throughout the period so disease problems can be detected early; loss of appetite is described as a very common, early sign of disease.[2] UF/IFAS notes that healthy fish should eat aggressively at scheduled feedings, while lethargy, gasping at the surface, or rubbing against objects can indicate illness.[6] Water quality should be monitored for dissolved oxygen, ammonia, nitrite, and pH at minimum, since low oxygen and high ammonia are both commonly associated with disease outbreaks.[6]Fish in quarantine can be sampled for diseases of concern at the beginning and end of the quarantine period, and testing for KHV may be done by direct methods such as virus isolation and PCR, or indirect antibody tests; however, no test definitively detects all carriers or survivors, and negative results do not guarantee a fish is pathogen-free.[1][2] Kodama Koi Farm states it operates its own on-site PCR device for faster KHV screening, in addition to sending samples to an outside laboratory running USDA APHIS–approved protocols.[11] For general diagnostic approaches, see diagnosis: scrapes, microscopes and fish vets and signs of illness.

The sentinel-fish test before full introduction

At the end of quarantine, several sources recommend placing a few fish from the new group together with a few fish from the established population in a separate area, away from the rest of the stock, and watching for signs of disease before full introduction; this can reveal problems with a smaller number of fish, though it offers no guarantee.[1][3] WOAH similarly recommends holding new fish with sentinel fish at permissive temperatures for KHV infection during quarantine.[4] Kodama Koi Farm describes adding a small koi from the home pond into the quarantine tank to act as a “canary,” noting that koi are social animals and that resident fish may already carry organisms the new fish are not immune to, or vice versa.[5]

Quarantine as part of wider biosecurity

Quarantine is described as one component of a broader biosecurity program that also includes animal management, good husbandry, sanitation, and disinfection.[2][12] Before acquiring fish, keepers are advised to ask suppliers whether there have been unexplained losses and whether any disease testing has been performed, and to request documentation of lab results.[1][2] Equipment, surfaces, and eggs can be disinfected using validated protocols; WOAH lists treatments such as iodophor, benzalkonium chloride, ethyl alcohol, and sodium hypochlorite at specified concentrations and exposure times for inactivating KHV.[4] Biosecurity approaches differ by setting: wholesalers handling high fish turnover generally cannot sustain the same depth of quarantine program used at long-term production or display facilities, due to cost and the sheer number and sources of incoming fish.[3]

Common questions

How long should new koi be quarantined?
UF/IFAS recommends a minimum of 30 days, including for KHV risk specifically.[1] WOAH recommends 4 weeks to 2 months for KHV biosecurity with sentinel fish.[4] Some commercial guidance describes 14–21 days of observation, though the same source extends its own quarantine to 30 days for KHV screening.[5][11]
What temperature should a koi quarantine tank be kept at?
For KHV detection, UF/IFAS recommends holding water at 75°F (24°C), since warmer temperatures promote disease expression if the virus is present.[1] Kodama Koi Farm recommends keeping quarantine water above 70°F so the koi immune system functions well.[5]
Should quarantine equipment be shared with the main pond?
No; sources recommend dedicated nets, buckets, and siphon hoses used only in the quarantine area, along with foot baths and hand washing, to avoid cross-contamination.[1][9]
Can quarantine guarantee new koi are disease-free?
No. Negative test results do not necessarily mean a fish is not a carrier, and there is no test that definitively detects all carriers or survivors of KHV.[1] A sentinel-fish test at the end of quarantine can help but offers no guarantee.[1]
Should salt be added to a quarantine tank?
A koi dealer source recommends adding non-iodized salt at about 0.1–0.3% to support the immune system during the transition, with up to 0.5% suggested in some scenarios; this reflects commercial hobbyist guidance rather than a university extension recommendation.[7][5]

References

  1. ^ UF/IFAS EDIS VM113: Koi Herpesvirus Disease (KHVD). University of Florida IFAS Extension (EDIS). ask.ifas.ufl.edu/publication/VM113. Retrieved November 2026.
  2. ^ SRAC Publication No. 4707: Biosecurity in Aquaculture, Part 1: An Overview. Southern Regional Aquaculture Center. srac.msstate.edu/pdfs/Fact%20Sheets/4707%20Biosecurity%20in%20Aquac…. Retrieved November 2026.
  3. ^ UF/IFAS EDIS FA101: Fish Health Management Considerations in Recirculating Aquaculture Systems—Part 3. University of Florida IFAS Extension (EDIS). ask.ifas.ufl.edu/publication/FA101. Retrieved November 2026.
  4. ^ Manual of Diagnostic Tests for Aquatic Animals, ch. 2.3.6 Koi herpesvirus disease (WOAH). World Organisation for Animal Health. woah.org/fileadmin/Home/eng/Health_standards/aahm/current/2.3.06_KH…. Retrieved November 2026.
  5. ^ Koi Quarantine Tank Setup & Procedures. Kodama Koi Farm (koi dealer). kodamakoifarm.com/koi-quarantine-tank-setup-procedure/. Retrieved November 2026.
  6. ^ UF/IFAS EDIS FA004: Introduction to Fish Health Management. University of Florida IFAS Extension (EDIS). ask.ifas.ufl.edu/publication/FA004. Retrieved November 2026.
  7. ^ How To Care For Your Koi Fish After Receiving It - Kodama Koi. Kodama Koi Farm (koi dealer). kodamakoifarm.com/koi-care-after-receiving/. Retrieved November 2026.
  8. ^ Quarantine (Wikipedia). Wikipedia. en.wikipedia.org/wiki/Quarantine. Retrieved November 2026.
  9. ^ UF/IFAS EDIS FA006: Ichthyophthirius multifiliis (White Spot) Infections in Fish. University of Florida IFAS Extension (EDIS). ask.ifas.ufl.edu/publication/FA006. Retrieved November 2026.
  10. ^ SRAC Publication No. 4712: Biosecurity in Aquaculture, Part 3: Ponds. Southern Regional Aquaculture Center. srac.msstate.edu/pdfs/Fact%20Sheets/4712%20Biosecurity%20in%20Aquac…. Retrieved November 2026.
  11. ^ Safely Managing Japan KHV Outbreak with New Processes and Technology at the Farm. Kodama Koi Farm (koi dealer). kodamakoifarm.com/managing-japan-khv-outbreak/. Retrieved November 2026.
  12. ^ UF/IFAS EDIS FA099: Fish Health Management Considerations in Recirculating Aquaculture Systems—Part 1. University of Florida IFAS Extension (EDIS). ask.ifas.ufl.edu/publication/FA099. Retrieved November 2026.