Treating Sick Koi

Treating Koi with Parasite Infections

Parasites have been a plague on the koi world since rice farmers in Japan first noticed these amazing color mutations in their food carp.  Parasites are found in all ponds, no matter how clear and clean your water is.  Parasites can be brought in by rodents, birds, even insects.  The most common way a parasite is introduced is through new plants and fish that you have purchased.  That is why proper quarantine is so important.  For more information on proper quarantine procedures for new koi please read this article.

Regardless of how the parasite got into your koi pond, it needs to be dealt with or eventually every koi in the pond could die.  Most parasites give you plenty of warning and you will be aware of the presence by the koi's behavior.  Some parasites, like Costia, give you only a couple days warning before it's too late.   Behavior often takes the form of flashing, which is a fast sideways movement against the side or bottom of the pond or an attempt to jump.  This is not playful activity, the parasites are irritating the skin of the koi and it is literally trying to scratch.  Another type of behavior that might indicate parasites is extreme lethargy and clamped fins.  They will sit at the bottom motionless with the fins clamped at the side.  This is caused by extreme stress and usually the stress is caused by parasites.  Also, watch for signs of dehydration, sunken eyes, loss of slime coat and very thin body.  This is often a sign of Costia, a very deadly type of parasite.

There are numerous treatments for the different types of parasites.  The best thing to do is determine which type of parasite you are dealing with before treatment.  This will allow you to be very specific in the treatment, saving you time and money, and reducing the stress on the koi.  The only way to determine the type of parasite is with a microscope.  This article will show you what the most common parasites look like under a microscope.

If a microscope is simply not an option and you are certain you are dealing with parasites because of their behavior, then a shotgun treatment is really the only option.  Many people will start with salt as the primary treatment.  To treat for parasites you will need to add up to 5 pounds of salt for every 100 gallons.  Yes, that is a lot of salt.  For more information on using salt in a koi pond, please read this article.  You can also do a salt dip.  This a high amount fo salt in a bucket of pond water, usually around 1 pound in 5 gallons.  This will kill parasites on the koi in seconds.  Never leave the koi in a salt dip for more then about 15 seconds, and if it rolls over, remove immedietly and place back in fresh water.  This will not solve the problem with parasites in the koi pond, but it will provide some short term relief to the stressed koi.  Salt will kill most parasites, but it will do nothing for flukes, anchor worms and lice.  Also, you cannot use salt with other parasite treatments that contain Fromalin, like ProformC or RidIch.  So if you want to use both ProformC and salt, start with ProfromC, do all three treatments, wait a couple days, then do a water change to make sure there is no fromalin left, then add your salt.  Both ProformC and salt treat for pretty much the same parasites, so usually only one is needed. 

To treat for flukes, the best treatment is Praziquantrel.  This will kill flukes very effectively.  Many times it is used with ProfromC as part of a shotgun treatment.  The Prazi is added at the same time as the third ProfromC treatment and then no water changes are done for at least 7 days.  Using ProfromC and Prazi together will kill off pretty much every type of parasite that will effect koi and can be seen with a mircoscope.  Sometimes you get very tough parasites that have built up a resistance to treatments and you may need to repeat the routine and possibly even double up the dosage, but this should be done only if the first round wasn't enough.  

There are also Anchor worms and fish lice to deal with.  However these can be seen without a microscope.  They are also easily treated with a product called ProfromLA.  This will be very effective at removing both anchor worms and lice. 

Many parasites won't directly kill koi, Costia being the biggest exception.  What parasites do is irritate and weaken the koi.  This creates the opportunity for bacteria to set in and start causing all sorts of infections, both external and internal.  The bacteria infections are usually what ends up killing the koi.  Once you have treated the koi for parasites, keep a close eye on them, in the weeks to follow you may have to deal with bacterial infections as well.     
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