What's in your medicine cabinet?
 It seems that no matter how well you take care of your koi from time to time they fall prey to some bacteria or parasite just waiting for the opportune time to multiply and attack your prize possessions.

So what's the answer?  It depends on your approach.  Some koi keepers just keep dosing chemical after chemical on them then just after you would think they are done they start with antibiotics.  This severely weakens the immune system of the koi and sometimes even shuts it down.  Others believe in survival of the fittest and do nothing until it's too late.  To treat or not to treat and when to start treating is a good question.

I have to admit I'm not a genius when it comes to koi diseases.  I still search for the "best" and fastest remedies that I can find.  What I do know is what I have learned myself through the suggestions of other people recommending products and procedures.  I really believe in using what has worked for me in the past.  My personal philosophy when it comes to treating any fish is this:

1. Treat when you know what you are treating.  It is important to properly diagnose the problem and treat the root of the problem not just secondary infections.  Stop guessing.  Calm down.  Get lab tests done if necessary so you know what you are treating.

2. I rather use chemicals than antibiotics if I have the choice.  Many koi breeders and wholesalers dose very heavily with antibiotics just because they think it will keep the koi healthy.  As a result koi are becoming increasingly more and more resistant to antibiotics. 

Being in the tropical fish business now for 10+ years I have personally witnessed this first hand.  I have been to may tropical fish hatcheries in Asia where all the fish are kept in antibiotics until they are sold.

3. Preventative maintenance is key.  Know what times of the year and what water temperatures in your area will trigger the most outbreaks.  For example in Portland spring and fall when the temps are warming up and cooling off can cause havoc with Aeromonas, and Pseudomonas bacteria.  It is up to you to be prepared with the med of choice ahead of time so you can stop it ASAP instead of reacting after it is well established in your pond.

4. React decisively, and swiftly.  Follow the directions for the treatment you are doing and complete the ENTIRE treatment.  Don't stop part of the way through it if they start looking better, or haven't changed yet.  Especially true of antibiotics.  They take 3-5 days to start working and should be used for 10 days. 

5. You need to know exactly how many gallons you are treating.  There is not any room for guessing.

6. What works for one person may not work for you.  Water hardness and maybe other factors effects the outcome and dosing levels of different chemicals.  It is always best to know the best dosing level for you and your water before you dose an entire group of koi.  Experiment on 1 koi first if you can.

7.  NEVER mix any medications chemicals or antibiotics unless you have been told to do so.  This also goes for salt. 

8. Be aware when using meds you may lose all the bacteria in  your filter.  Yes, you probably need to treat your filter as well, so don't bypass it. 

 

That being said here are the meds we both use and recommend.

 

Debride® ointment is a petroleum based medication containing anti-inflammatory and topical anesthetics. Debride® ointment is great at cleaning wounds and helping to speed healing when applying to an ulcer or body sore in Koi or Goldfish.   Previously sold under the name Lymnozyme, Koizyme is a liquid containing bacteria and enzymes designed to kill & outcompete the bacteria which cause ulcers in Koi.
KoiMedic Salinity Meter is an electronic (probe type) tester for measuring the salt level of your pond.   MelaFix gained widespread acclaim by speeding the healing process from Ulcers, sores, bruises, scale loss, etc.
Potassium Permanganate (KMnO4) is a purple granular powder that kills 99.9% of exposed pathogenic bacteria.   Prazi Pond Plus is the hands-down best treatment for flukes available to pond keepers. It is the most gentle, yet effective treatment and also rids fish of any internal parasites or worms.
         
ProForm-C is a Broad Spectrum Disease Treatment.   ProForm-LA is the safest and most effective treatment for the control of diseases of pond fish caused by Lice and Anchor Worms.
         
When applied to the water of ornamental Koi, Supaverm eliminates fluke (trematode) infestations within 3 days. Not recommended for inexperienced hobbyists.   As good as injections! Tricide Neo® is a bath treatment made with a convenient packet of crystals.
         
2006 Reloaded Edition. This is THE book for everything you need to know about caring for koi fish, by the renowned Dr. Erik Johnson.