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  • Page 2 of 2 FirstFirst 12
    Results 21 to 27 of 27

    Thread: Lost 50% of my koi over last 7 weeks... flukes?

    1. #21
      kdh is offline Senior Member
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      Did you ever take readings of your water before the problem? If so what were they?

    2. #22
      SJK is offline Supporting Member
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      Since you've had a vet identify a fluke problem but nothing else let's go back to some basic water quality issues:

      1) Have you added any new fish in the last few months? Do any of the fish that have died, or are ill, have a notch across their nose? The vet didn't find signs of costia, but it and KHV tend to kill large numbers of fish quickly. So if they have notched noses and new fish were added, it could be KHV. As RTB noted, the salt should have killed other parasites. An FM&G treatment normally might be warranted if the fish are strong enough to handle it, but since the vet didn't find other ones, its back to water quality issues.

      2) Your water quality shows traces of ammonia, nitrite and nitrates. The ammonia and nitrite readings of 0.25 (your possible high end) indicate the bio-filters may not be not keeping up with the fish load, so two issues to explore here.

      First, a 20,000L pond is about 5,300 gallons which would support 530" of fish max at 10 gallons per inch of fish. The pond had a minimum of 720" using a calculation of 40 fish at an average 18" per fish (avg of 30-60 cm). So it was ~35% overstocked. In early years not a problem but as fish continued to grow, the filtration system may have hit an overload problem. If your water quality looks poor (dull/not clear, etc.) and your ammonia and nitrite reading keep increasing, it indicates the filtration system may not be keeping up. (Sadly, having lost 1/2 the fish, the load is now about 360" so the filters may catch up going forward if this was a problem.

      Second, you mention having a set of Japanese mats as the only filtration. Does this serve both mechanical (removes leaves, poop and debris) and bio-conversion (houses the nitrifying bacteria) filtration? And what is your filter maintenance practice? How often you rinse the Japanese mats? The system may have built up over the last year to where it is overloaded and is no longer functioning properly. It would help to know what your regular maintenance practices are. You mentioned frequent water changes, which is excellent. Do you want to come in from a well or is it tapwater?

      And finally, as this has us all puzzled, what is the length, width and depth of your pond and what kind of shape is it? You mentioned it only has the one water return from the filter area. As it's a good size pond, it's possible that the water circulation in the pond is leaving some areas of water stagnant. I checked the air temperature in Sydney and it's a beautiful 80° on average, so it doesn't seem like water temperature would be an issue.

      I'm sorry you're experiencing these losses. As a new pond owner (inherited with house) myself, it would be devastating to lose beautiful fish in an established pond despite the work you're doing. Please keep us posted.

      Sue
      Last edited by SJK; 01-10-2021 at 01:00 AM.

    3. #23
      coolwon is online now Senior Member
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      You added air and stones to your pond?

      Would that have been before or after the loss of the fish?

      Are you still losing fish?

      I presume you use sodium thiosulfate when you do your water changes, and wash out the Japanese filter matting using your pond water to preserve the inhabitants.

      Garfield
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    4. #24
      kuvesh is offline Junior Member
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      Thanks for all the feedback – back at work now and short on time, so apologies for the delayed update:

      4 days after the first praziquantel dosing, the fish behaviour was still worrying – seldom flashing but overall low activity level, still preferring to hide and zero appetite. (I cant find any info on how fish react to praziquantel, so would be keen to hear from others if this is normal.)

      Did a 40% water change and thankfully within 48 hours fish started eating again (barely) but enough for me feed anti-biotics in the food for 5 days. Over the antibiotic period fish activity level increased, maybe 65-70% back to normal but not like the old days darting around and charging for the food.

      Earlier this week (2 weeks since initial praziquantel treatment) I noticed a few fish flashing. I was amazed one fish actually did 3 jumps in a row, like it was in the Olympic hurdles. Never seen that before.

      Decided to give a second dose of praziquantel today – this is 17 days after my first treatment. Like before, now all fish are out and about again – close to surface, not gasping for air but floating around. They definitely know prazi is in the water…

      Plan to keep it in for 4-5 days again depending on their behaviour. This time I have not added salt. Current salinity is close to <0.05%. I might add salt in the next day or 2 to 0.2%

      Quote Originally Posted by kdh View Post
      Did you ever take readings of your water before the problem? If so what were they?
      In hindsight, not properly. Through this experience have learnt a few things about using the API test kit..

      Quote Originally Posted by SJK View Post
      ….

      Second, you mention having a set of Japanese mats as the only filtration. Does this serve both mechanical (removes leaves, poop and debris) and bio-conversion (houses the nitrifying bacteria) filtration? And what is your filter maintenance practice? How often you rinse the Japanese mats? The system may have built up over the last year to where it is overloaded and is no longer functioning properly. It would help to know what your regular maintenance practices are. You mentioned frequent water changes, which is excellent. Do you want to come in from a well or is it tapwater?

      And finally, as this has us all puzzled, what is the length, width and depth of your pond and what kind of shape is it? You mentioned it only has the one water return from the filter area. As it's a good size pond, it's possible that the water circulation in the pond is leaving some areas of water stagnant. I checked the air temperature in Sydney and it's a beautiful 80° on average, so it doesn't seem like water temperature would be an issue.



      Sue
      My filtration system is very basic. Pump from pond uphill into filter box which holds the Japanese mats then back out to pond. Its gravity (because junk goes down into the mats) but the water exit is from the water line of the filter box (same height as entry but on the opposite side).

      The pump in the pond has a cover so large debris doesn’t get pumped to the filter box. Leaves and other debris I fish out manually from the pond floor. The pond is sloped so rubbish mostly moves to the deeper end or floats.

      The Japanese mats in the filter box are stacked 3 wide and at least 6 deep (never counted). In past the filter box went months without cleaning (I had a pond guy come to help occassionally) but now I do myself every 2-3 weeks. Now I only remove the top 1 or 2 layers given the grime does not seep down much with regular cleaning.

      I am looking into a DIY upgrade to my filter. Considering adding a layer of hydroton or pumice below the Japanese mats. A koi enthusiast I met suggested that. Seems easy enough.

      Re water changes, in the past I just did top ups to the pond once a week to cover the evaporation. Now I do one or two 20-30% water changes a week.

      Pond dimensions – effectively a rectangle approx. 12m long and 3.1m wide. In terms of depth, best to describe as split into 3 lanes, the centre lane is 1.4m wide and average depth 0.7m. The 2 side lanes are 0.3m deep. The filter box is 1.1m x 1.9x x 1m and holds all the Japanese mats. A walking bridge runs over the centre lane. Some pics attached fyi.

      Quote Originally Posted by coolwon View Post
      You added air and stones to your pond?

      Would that have been before or after the loss of the fish?

      Are you still losing fish?

      I presume you use sodium thiosulfate when you do your water changes, and wash out the Japanese filter matting using your pond water to preserve the inhabitants.

      Garfield
      Air stones were added just after I lost my first couple fish. Haven’t lost a fish since beginning of Jan.

      When I add tap water I use Seachem Safe. Used to use Prime but was getting too expensive given the size of my pond.

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    5. #25
      RichToyBox's Avatar
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      I could be wrong, but I don't think that you are getting the best use of the matting in the filter. Most of the water is going over the top and not down and through the mat, so much of the mat is not seeing any nutrients. I think that if you turned the mat on edge transverse to the flow, extending above the water line would force the water to use much more of the mat and provide better filtration. I don't know that that is an issue, just a comment.

      It kind of sounds like you may have gill flukes, which are egg layers rather than live bearers. With live bearing skin flukes, you kill the adult, you also kill the baby. With the egg laying gill flukes, the egg is not impacted by the Prazi, so the egg has to hatch and the baby become adult like. For gill flukes the Prazi is dosed at least twice, about a week apart and allowed to remain for the week duration. It is a temperature dependent time with warmer water causing faster hatching of the eggs, so shorter times are found effective, but during colder climes, the time for hatching may be long enough that a third dose is needed.

      "Our goal is to assist with emergency and Koi health issues, as well as educate on best practices. Please help us gain a clear picture by giving the original poster time to answer our questions before offering opinions and suggested treatments."

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    6. #26
      SJK is offline Supporting Member
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      Beautiful and unique pond set up. Richard helped me understand that it could take 2-3 weeks after a successful fluke treatment for the fish to stop flashing. Praziquantel causes flukes to spasm and koi may continue to flash due to discomfort while flukes dislodge and koi heals. First they are bothered by the flukes dying, so they flash. And then, just like in a human, the open wound the flukes create has to heal and it itches as it does. My fish moved from heavy flashing to rubbing against the bottom of the pond over a 2 1/2 week period. It was only three weeks later that they completely stop flashing.

    7. #27
      kuvesh is offline Junior Member
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      Quote Originally Posted by RichToyBox View Post
      I could be wrong, but I don't think that you are getting the best use of the matting in the filter. Most of the water is going over the top and not down and through the mat, so much of the mat is not seeing any nutrients. I think that if you turned the mat on edge transverse to the flow, extending above the water line would force the water to use much more of the mat and provide better filtration. I don't know that that is an issue, just a comment.

      It kind of sounds like you may have gill flukes, which are egg layers rather than live bearers. With live bearing skin flukes, you kill the adult, you also kill the baby. With the egg laying gill flukes, the egg is not impacted by the Prazi, so the egg has to hatch and the baby become adult like. For gill flukes the Prazi is dosed at least twice, about a week apart and allowed to remain for the week duration. It is a temperature dependent time with warmer water causing faster hatching of the eggs, so shorter times are found effective, but during colder climes, the time for hatching may be long enough that a third dose is needed.
      I was thinking the exact same thing on the filter... its not efficient. On the next water change I am planning to:
      1. Add a layer of hydroton or pumice across the bottom of the filter box to help improve biological
      2. The layer of hydroton will free up some matts which I can then place vertically to pierce the waterline between the 3 stacks of matts. This effectively creates 3 chambers in the filter before the exit.

      You could be right on the gill flukes but not what the vet found... in any event, I see a lot of positive feedback on Fluke-M and Fluke-S. We can't that locally in Australia but found a UK ebay seller that frequently delivers to Australia. I plan to order a few doses to have in hand and also try if things don't improve in coming weeks.

      Quote Originally Posted by SJK View Post
      Beautiful and unique pond set up. Richard helped me understand that it could take 2-3 weeks after a successful fluke treatment for the fish to stop flashing. Praziquantel causes flukes to spasm and koi may continue to flash due to discomfort while flukes dislodge and koi heals. First they are bothered by the flukes dying, so they flash. And then, just like in a human, the open wound the flukes create has to heal and it itches as it does. My fish moved from heavy flashing to rubbing against the bottom of the pond over a 2 1/2 week period. It was only three weeks later that they completely stop flashing.
      Thanks for sharing and I hope the same happens for my fish!

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