Koi Rescue
Phoenix Arizona

Koi Diseases and Parasites

Ways Parasites & Diseases get into your pond

Everyone talks about quarantinging new fish that are introduced to your pond, but you might not realize that almost all koi carry diseases with them, sort of like how humans carry strep throat. And just like strep, when the pond conditions deteriorate, the koi get stressed, and some diseases can start to emerge and affect your fish.

Birds also transmit many things in and out of your pond. They stand in the water, dip their beaks, splash around etc. Parasites often stick to the birds, then when they go to the next pond, the parasites get dropped off. Some of the stuff is transmitted through their poop.

Koi Disease Identification and Treatment

I am not a koi health expert. I have been to a couple of seminars, have read a few koi health books, and have treated numerous fish and cured them of common problems, mostly with "shotgun" aproaches using multiple medicines at the same time. The real experts scrape fish & take clipping samples, examine those under a microscope to detect parasites so they can do specific treatments. Also a professional can take blood and fecal samples to have analyzed by a lab to determine exact baterial problems.

I highly suggest you get some books about koi health. Some of the information in the books contradict each other, so what I do is have several of them. When I have a problem, I read the apropriate sections in each one to try and figure out the best course of action. The book I use the most is the Manual of Koi Health (see it in the list of books below).

The books also have pictures of koi that are affected by the various diseases, so if your koi starts to have a problem, you can look in the books to find a matching sick koi and treat accordingly.

Are rescue koi healthy?

Some yes, some no. Ironically the koi that came from the scottsdale golf course ponds were examined by a vet at the koi seminar, we did scrapings and gill clippings and both showed that the koi were without parasites and very healthy. The vet said the reason for that is because in a natural pond, mother nature has a balance for everything and there are organisms that feed on the parasites, which attack koi. We also took scrapings and clippings from koi purchased as Walmart - and those fish were covered in parasites. The reason being is that they have a central filter system that supplies all the tanks, so if one fish has parasites, they all get the parasites.

Most koi that come from backyard ponds do seem to be healthy and parastie free, that is because they have usually been isolated from other koi for a long time and if there were problems, either they would have died or the previous owner would have treated and fixed the problems.

All that being said, you really should you quarantine any new fish coming to your system. Every koi pond owner should have a quarantine system (QT) which includes a tank such as a 100+ gallon (or larger) stock tank or play pool, net cover, filter, circulation pump and/or other aeration device. As a koi owner, your koi might run into problems later on and it is good to have. If you rescue koi on a regular basis, you will want to have this secondary system for the koi you adopt out.