Under ideal conditions, the water in the quarantine tank should be the same temperature and pH as the wat4er in which the koi has been swimming over the last couple of weeks. If this is not possible, then try to get as close to the temperature as practical, remembering that koi tolerate a rise in water temperature better than a drop.
The koi to be isolated should be contained in a transport bag with adequate water and oxygen and floated in the isolation tank water for 20 to 30 minutes to allow for temperature equilibrium between the water in the bag and in the tank.
Fish (but not transport water) should be released into a properly sized container (koi tub) of clean quarantine tank water and subsequently the fish should be quickly transferred to the tank. If the hobbyist is not competent to handle the fish with bare hands, the transport bag should be used to transfer the koi and should contain as little water as possible, the goal being to minimize the amount of transport water put into the quarantine tank.
The fish should be kept quiet and under cover of Styrofoam or pvc pipes
The temperature of the water in the Q-tank should be adjusted and held between 70 to 75 F for a period of no less than three weeks. During the temperature adjustment period, the temperature should not drop or raise more than 5F per day.
Do not feed the koi for the first few days. Then, if the fish appear hungry, start feeding a little twice per day.
Over the entire period of quarantine, be sure to monitor water parameters, particularly ammonia, nitrite, pH alkalinity, and temperature and make any necessary adjustments and/or take appropriate measures.
Water changes are usually beneficial, are recommended and a minimum of 10% per day is advisable. Always dechlorinate new water used for water changes and use an ammonia binder if the water contains chloramines and you are changing over 20% or if you do not have a working bio-converter on the system.
The fish should be maintained at 70-75 F for no less than three weeks and a much better period would be three months.
The longer the quarantine period, the more likely infected fish will be revealed.
At some time during the quarantine period, a fish of "lesser desirability" from your pond should be placed in the tank with the new arrival(s). Koi are social animals, and need companions. However, if there are more than one koi in quarantine, the pond fish can be added after 1-3 weeks in quarantine, and the population kept for 3 weeks to 3 months more. By waiting until 3 weeks, many diseases, including KHV will become obvious, and can be eliminated before any pond fish are at risk.
During the period of quarantine, periodically check (or have a professional check) for any other abnormal or disease conditions. It is advisable to have a complete and accurate diagnosis of conditions found in quarantine, make sure that the quarantine system has good water quality and follow expert advice for keeping koi healthy. Monitor the tank daily and if any fish (new or old) shows the symptoms typical of KHV, call a qualified veterinarian to take samples and submit them to a qualified lab for testing. For a list of qualified veterinarians, see the AKCA web site at:
www.akca.org and follow the "KHA" link then the "Referral Veterinarians" link. If maintained at the 70-75 F temperature with no attempt to otherwise support the fish or suppress opportunistic pathogens, about 10% of the fish should be expected to survive.
KHV infected koi may be euthanized (humanely killed) and disposed of properly to prevent spread, or an attempt may be made to save the fish. One method reported successful in saving a substantial percentage of KHV infected koi is to elevate the temperature of the tank water to 86 F until the fish recovers. Others (see previous section) involve adding chemicals to the water to treat the symptoms of sick fish and possibly to prevent transmission of virus. Remember there is no cure for KHV.