Koi loss of appetite


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Hi all . My first post and hope you can advise . Have an outdoor 12000 gallon swimming pool that I converted 15 years ago to a fish pond and have 6 large Koi about 18”+ and 15 or so small goldfish and Koi . The large Koi have lost there appetite , weather is cool at present and the ph is about 7.5 / 8 . The water is unusually clear and they are congregating at the shallow end . I have plants all around and have a large filter . I occasionally run a water change from a large lake I have on the property ( I pump out pond water and pump in lake water at the same time ) the fish love this lake water and they sit under the lake flow coming in , so I assume this water is better than the pool water as they love it . I see test kits are available to test for all sorts of things but have only tested for ph , should I test for something else ? Richard
 
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Welcome @rjbpond ! So only the large koi are not eating? And hanging out in the shallow water. I was going to suggest maybe you have had some predator activity but that would normally send them deeper. Any other signs of unusual behavior? Clamped fins? Redness anywhere?

This one will have me thinking... low oxygen affects larger fish first, but they aren't gasping at the surface. Toxins would affect all the fish, and generally the smaller fish would show signs earlier than the bigger ones. The fish hanging out under the water being pumped in doesn't necessarily mean the water is better - koi are naturally river fish and they love currents and flowing water. Plus there might be some tasty little tidbits floating in with that water!

Post some pictures of your pond if you can - sometimes seeing things can give some clues.
 
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Hi and thanks for your reply and interest . Big pond , 30 x 17 foot and 3 foot to 7 foot deep , get little direct sunlight as there is a large Catalper tree that shades most of it . Don’t get any blanket weed and stays reasonably clear , hav’nt got any oxygenating plants in ( very clear at present ) , converted it to a pond 15 or 20 years ago and put a submerged frame around the edge to carrie black crates for plants . Oxygen a bit low between 2 and 5 , two fountains run 7 am till 9pm but the 1 hp filter pump I run about 12 hours a day . They are feeding a bit better today except Dyson he’s always on front row and the fish are bigger than I said as one is about 30” and 5 others about 24” plus the small ones . The large Koi do like the lake water and stack up under the 4” return pipe but when I return the pump to recirculate they loose interest , the lake oxygen is the same as the pond . Have added a couple of pics.
20190812_151036.jpg
20190812_151045.jpg
 
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I am certainly not a expert..... but I do have some experience with large Koi...... high ammonia levels is definitely a sign to Koi.... hey the ammonia is high......I need to quit eating so much . Also the fresh water coming in that gives them some relief from the ammonia.....just a thought
 
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I am certainly not a expert..... but I do have some experience with large Koi...... high ammonia levels is definitely a sign to Koi.... hey the ammonia is high......I need to quit eating so much . Also the fresh water coming in that gives them some relief from the ammonia.....just a thought
 
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Hmmm.... just reading your post real quick and one thing popped out - you don't run the filter 24/7? That's a problem if that's the case. Any bacteria in your filter will die off.

Off to read more closely! Also - WOW! What a gorgeous pond!
 
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I know you have had the pond for years as is evident by the spectacular plants around the pond but all i can see is a simple fountain for the addition and maintaining the o2 levels. I would get a Nitto air compressor going ..no they are not cheap but from what i have seen they are quiet comparatively and they last.
The pump not running constantly will create other issues the bacteria in the filters and or pond can choke and die from lack of 02. as the fish grow so can the parameters for what works and what no longer works. The ammonia if an unusual event may have happpened can spike rather quickly. Not knowing more and the history i would run the pump 24/7 .get good supply of air going and no not an aquarium air pump. and add start right which is an aquarium product that helps fish build up there slime coat which is crucial for there health.
 

addy1

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Love the bird fountain. Agree with the above run the pump 24/7, add a aerator.

Your pond is beautiful!
 
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You have such an amazing setup absolutely beautiful. I can see your fish through the reflection in a couple of the pics . You said you had a large filter . what type? As your pumps work to add o2 to the water your filter is probably trapping and reducing the levels.
Another food for thought for you that I can totally see in your set up is a raised bog with a water fall or even a simple weir where a sheet flow of water drops into the pond. The raised box can be made out of anything and could compliment your already stunning setup and provide clear healthy water. I'd probably look at building a 20" to 24" inch wide x 16' feet long and 2 foot deep bog in the shape of an L and build it where you have those blue pots.
 

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