It is very common for a hobbyist to purchase a new koi fish from a pet shop or koi dealer, take the fish home then immediately add it to their pond only to watch it die a few short weeks later.  Why does this scenario get repeated so often?  All your existing fish still inhabiting the same pond seem just fine.  Did you purchase sick fish?  Or worse, did your koi dealer knowingly sell you a sick fish?  Not likely. In our experience, most koi losses result from three factors which conspire together to create the perfect storm for new koi additions. These three deadly factors include (1) increased koi stress levels, (2) common koi parasites, and (3) resulting bacterial infections.

While koi are relatively hardy fish, they also serve as hosts to various parasites. These deadly parasites, including flukes and costia, can often be found during routine scoping within virtually any established pond.  While it is impossible to permanently eradicate all koi parasites from any pond, there are several proactive steps koi keepers can take to help keep parasite numbers in check while ensuring optimal koi health.

First and foremost, koi immune systems require exceptional water quality delivered by sufficient koi pond filtration.  Great care should always be taken to help avoid overstocking and overfeeding.  These issues can quickly result in poor water quality and deadly ammonia spikes, which can quickly result in sick koi and even fish losses.  To ensure exceptional water quality, we highly recommend professional grade Elite Optimus III Koi Pond Filters.    

Regular preventative treatments — including salt, KOI BIO SHIELD, KOI PRAZI, potassium permanganate, and KOI NITRO can significantly help to prevent parasite outbreaks and resulting bacterial infections. 

Large koi fish require a properly designed large koi pond to thrive, and contrary to what you may have read elsewhere, a koi pond and a water garden are not the same thing!  Practicing sound koi quarantine procedures for all new koi additions before adding them to your main pond is also strongly recommended regardless of source.

Proper Koi Pond Design:

A shallow planted water garden full of rocks and gravel is NOT a proper koi pond.  Trying to safely keep large koi in a typical Aquascape design water feature is a recipe for disaster. And regardless of what your “certified” landscaper may claim during a sales pitch, large koi will NEVER find “balance” within a hastily built, poorly designed water feature. 

Proper Koi Pond Filtration:

A skimmer filter, waterfall filter or small canister filter are NOT sufficient for large koi fish.  These inferior systems cannot handle the amount of waste produced by large koi, which results in poor water quality and a higher maintenance workload for the pond owner. 

Weekly Pond Maintenance:

Hobbyists should be diligent about cycling their pond filters on a weekly basis, while also doing partial water changes. These steps are critical to help maintain a healthy ecosystem for large koi fish. 

Avoid Overstocking:

Koi collecting can become quite an addicting hobby, but you must also show some restraint to avoid overstocking your pond to ensure optimal koi fish health. Many hobbyists to overstock their ponds and grossly overstock their quarantine tank (QT) setups when acquiring new koi. While many  hobbyists purposely oversize their pond  filter systems to accommodate a higher stocking rate, overstocking a koi pond or QT is still never a good idea. With proper filtration, hobbyists should allow a minimum swim area of 150 gallons for each large koi fish up to 24”. Sadly, hobbyists who violate this rule will often experience ammonia spikes and fish losses.

A simple point calculation system can also be used to help avoid overstocking.  To maintain optimal water quality, the goal is to maintain less than 50 koi stocking points per 150 gallons. Large koi increase bio load more than small koi, therefore they account for more points.

Rule: Maximum 50 koi stocking points per 150 gallons

To quickly calculate koi stocking points:

Koi Size Point Values:
 Up to 9” Koi = 1.5 Points each
  9-12’’ Koi =  3 Points each
  12-15’’ Koi = 6  Points each
  15-18’’ Koi = 9  Points each
  18-21’’ Koi = 12 Points each
  21-24’’ Koi = 15 Points each
  24-27’’ Koi = 20 Points each
  Over 27’’ Koi = 25 Points each

Add up all points to calculate gallons needed to safely accommodate the bio load presently in your pond or QT.

Avoid Overfeeding:

The more you feed your koi, the more waste they produce, and this can wreak havoc on pond water quality. Never feed your koi more than they will consume in 5 minutes and always remove excess uneaten food from pond.

Regular Preventative Treatments:

Many common koi parasites, including flukes and costia, exist in virtually any established pond so parasite outbreaks can occur very quickly.  Regular preventative treatments can greatly help to keep parasite numbers in check while ensuring optimal koi fish health.  Treatments we recommend and often use ourselves include salt, KOI BIO SHIELD, KOI PRAZI, potassium permanganate, and KOI NITRO. 

Quarantine for New Koi Additions:

Regardless of source, we strongly recommend hobbyists follow strict quarantine for all new koi additions before adding them to an established pond with existing fish. 

Essential MUST-HAVE Koi Treatments:

We strongly recommend koi keepers always keep the following products readily available to help ensure optimal koi health and to treat various issues as they occur.

Salt: Effective and relatively safe treatment for most common koi parasites

KOI PRAZI: The most effective treatment for salt-resistant flukes, including both gill flukes and skin flukes, as well as other salt-resistant parasites commonly found in koi ponds.

KOI BIO SHIELD: Helps to eliminate deadly anerobic bacteria commonly found in koi ponds, which often result in deadly bacterial infections.

Potassium Permanganate (PP): The most effective treatment for salt-resistant costia and other salt-resistant parasites commonly found in koi ponds.

KOI NITRO: Highly effective treatment for bacterial infections, often resulting from parasite outbreaks and deadly anerobic bacteria found in koi ponds.