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  1. #1

    Koi Illness or disease

    My Koi fish have suddenly come down with some type of disease or illness which has killed many in the last 2 weeks. 2 weeks ago I left for vacation, no issue visually, then 2 weeks later issues as shown in the photo attached, I have both Kio and comets, and comets are unaffected at this point. I have treated the pond with Melafix and pond salt, and have ordered Knock-out from you which I should receive tomorrow. If you can help with a diagnosis it would be greatly appreciated... I have about 5o koi, and concerned I will lose them all. Please note I live in northern US, so the water temperature has lowered considerably over the last month.
    Kio Illness.jpg

  2. #2
    Water parameters are the first thing to check because bad parameters can cause health problems directly or weaken the immune system so that a fish succumbs to a parasite or pathogen it could otherwise have resisted. Even if poor water quality doesn't play a part in initiating a health issue, koi have a much better chance of recovering in good water than in bad.

    The minimum parameters you should check are pH, ammonia and nitrite. Nitrate and KH can also give valuable information to help interpret other parameters and oxygen should be checked if there is any sign of fish gasping at the surface or crowding around waterfalls etc. To make a proper diagnosis we need actual values not “all ok” etc.

    If any water parameter is incorrect it should be brought to an acceptable value as quickly as possible so as not to unnecessarily delay any medical treatment that may subsequently be needed.

  3. #3
    Checked the water quality, Nitrates - 0, Nitrites - 0, total hardness - 300ppm, KH ppm - 0, PH - 6.3

  4. #4
    I thought that might be the case. A common reason for fish dying at this time of year is a pH crash and with 0 KH and your pH test showing as low as it can, that's exactly what you have.

    A common reagent used for measuring pH is Phenol Red which is a good reagent for the koi hobby because it's easy to determine the colour changes for the different pH levels across its range. It becomes increasingly yellow as the pH value falls until just below about 6.5 when it has become as yellow as it can go so it can’t read values much below that. So, if a pH test shows yellow which appears to correspond to 6.0 or 6.5, the actual value may be very much lower and the pH may even have crashed to a life threatening value but the kit can’t show it.

    You must raise the pH immediately, starting tonight if you can, because the pH will continue to fall killing more fish. Below is a link to an article on my website that explains how to do this safely, without causing further stress which may possibly prove fatal to some badly affected fish at this stage. If you don't have any sodium bicarbonate (baking soda) and can't get any tonight, you can help mitigate any further losses by doing an immediate 20% water change.

    With no ammonia test, I'm guessing that you're using test strips. I'll give more advise later after you've begun to raise the pH to an acceptable value but start with the sodium bicarbonate first or, at least, do an immediate 20% change to prevent the possibility of further losses.

    Last edited by Manky Sanke; 07-12-2022 at 06:24 PM.

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  6. #5
    Senior Member Rank = Sansai PeterDunn's Avatar
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    Jun 2020
    Wednesbury,West Midlands
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    Hi mike
    Aldi have bicarb at 59p they are open till 10pm

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  8. #6
    Thanks for the valuable information. I have started to raise the PH and have an ammonia test kit on order. My online pond store recommended that I treat the pond with the attached, and I have ordered it. Do I still need to use to get the fish back in order? I put salt in the other day to help.
    Attached Images Attached Images

  9. #7
    Great that you've already started to raise the pH. How do the fish look today and were there any more losses overnight?

    Personally, I wouldn't have suggested using Knock Out or salt. Knock Out is just a broad spectrum anti parasite treatment and, although salt is an excellent medication when it's the correct treatment for a diagnosed parasite infection, koi are freshwater fish so they do best in fresh water. It isn't practical to remove the salt, that will slowly reduce with future water changes, but raising the pH is all that you need to do at the moment so I would save the Knock Out in case it's needed later.

    Just follow the advice on my site until you get the pH back to it's usual level and, in case the fish start looking for food, don't feed them until the biofilter (bioconverter) has recovered to prevent an ammonia and or nitrite spike. I'm guessing the in the Northern US the water temperature will be cold and getting colder so the biofilter may not fully recover until spring.

    Now the pH has started to rise, the advise I was going to give about test kits would have been to throw away the test strips and use a manual (drop type) test kit and use it to test the water weekly in summer but at least monthly during winter.

    Here in the UK, the advise I usually give about test kits is that, when I was asked to product test some (UK) test kits, the API Freshwater Master Kit proved as accurate as you can expect from a manual kit. They arenít the cheapest but they are accurate and very economic because you get a generous amount of reagent so you donít have to keep buying replacements. You can buy them both on eBay for under £40 on the links below. This is from a UK supplier but they are also available in the US via your versions of eBay or Amazon.

    About half of the students I teach on line are from the US or Canada and many prefer the Seifert range of kits. These are equally as good so you may choose which you buy especially since you've already ordered an ammonia kit.

    Freshwater Master kit:
    Choose KH kit from this listing:
    www.ebay.co.uk/itm/165579840550?_trkparms=amclksrc%3DITM%26aid%3D1110 01%26algo%3DREC.SEED%26ao%3D1%26asc%3D201801050958 53%26meid%3Db5850353d0764f11a33381a7918dd640%26pid %3D100903%26rk%3D1%26rkt%3D20%26sd%3D165579840550% 26itm%3D165579840550%26pmt%3D0%26noa%3D1%26pg%3D25 10209%26brand%3DAPI&_trksid=p2510209.c100903.m5276

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