Koi are wonderful, interactive and beautiful fish.  Unfortunately they do get sick just like any other animals.   Introducing a new fish to a pond without proper quarantine can have disastrous results because it can also introduce parasites, viruses, bacteria or other diseases into an established pond.   This can be devastating emotionally as well as financially.  Identifying problems in quarantine is easier and less expensive than allowing anything to get into the main pond.

The minimum quarantine period for new koi should be 30 days.  This needs to be in an isolation tank, hospital tank or separate pond far enough away from the main pond that water cannot splash from one to the other.  If introducing multiple fish, the 30 day period begins as a group after the last fish is placed into the quarantine tank.  In other words, if you purchase a new fish 20 days into quarantine, then ALL fish in quarantine should start again at day 1. 

The water in the tank should be kept between 68-75 degrees Fahrenheit.    When feeding or doing water changes, the quarantine fish should be done last to minimize risk of moving water and disease from the quarantine tank to the main pond.  All nets should be designated specifically for that tank.  The quarantine fish should be fed normally and observed daily for any signs of illness (flashing, rubbing, piping, decreased food intake, poor energy, etc.).  Any signs of illness or any deaths should be investigated until a cause is found and treated if necessary.  Water quality should be tested and maintained well throughout the quarantine period. 

Ideally, fish in quarantine should also be examined for disease.  Skin scrapes and gill biopsies can identify any parasites the new fish may have and allow them to be treated in a quarantine tank far easier and cheaper than after it is allowed to get into the main pond.  Hoi Herpes Virus (KHV) testing should be done as well.  We recommend testing at least 10% plus one of the quarantine fish.  In other words, if 20 fish are in quarantine, then at least three should be tested for parasites and KHV.  This should be done 2-3 weeks into quarantine to allow enough time at the designated temperatures to avoid false negative testing.  Obviously, the test results should be back and parasites eradicated prior to moving into the main pond. 

In a large pond with very large fish, this may require a smaller pond or a show tank in the garage in order to allow several hundred gallons of filtered water, but that is a good thing to have available if you have a very large collection.  If one gets sick and needs treatment, it can be difficult to catch an individual fish daily in a 20-30 thousand gallon pond.  If you have a smaller pond and you are introducing younger fish an aquarium can be used for quarantine.  A cattle watering trough can also be improvised into a quarantine system fairly easily.  Either way, quarantine can be designed to be cheaper and easier than dealing with parasites or other disease introduced to the main pond. 

Summary:
• 30 days minimum time from the time that the last fish was placed in quarantine.
• Use different nets and supplies for quarantine tanks
• Feed quarantine animals last to avoid cross-contamination from water.
• Keep the water temperature between 68-75F throughout the quarantine time.
• Test for diseases and parasites 3 weeks into quarantine.
• Investigate any signs of illness promptly.