How JustAnswer Works:

  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.

Ask Dr. B. Your Own Question

Dr. B.
Dr. B., Board Certified Veterinarian
Category: Vet
Satisfied Customers: 16268
Experience:  General practice veterinary surgeon with extensive experience in a wide range of species.
60269376
Type Your Vet Question Here...
Dr. B. is online now

One koi has died with no visible signs and two more are very

Customer Question

One koi has died with no visible signs and two more are very lethargic and not social with other fish, they are on the surface water all the time. What can I do
Submitted: 3 years ago.
Category: Vet
Expert:  Dr. B. replied 3 years ago.

Hello & welcome, I am Dr. B, a licensed veterinarian and I would like to help you with your wee ones today.

 

Have you checked your water parameters (pH, nitrites, nitrates, ammonia)?

What were your findings?

 

What is the pond temperature?

 

Does this pond have aeration?

Have you turned off your filters recently?

Any recent changes to the pond?

Customer: replied 3 years ago.

Hi,


Water parameters are fine


 


Pond temperature is 7 degrees


 


pond has not had aeration since september


 


filters have not been turned off


 


and not changes to the pond apart from the death of one fish already


 


 


 

Expert:  Dr. B. replied 3 years ago.

Thank you for the further information.

The fish are certainly not giving us much to go on. The lack of extenal clinical signs of the deceased fish does allow us to rule out skin based disease (ie parasite, bacterial, fungal) and as long as it wasn't distended nor showed red streaking of the fins/tail/flanks then internal bacterial disease (either causing dropsy or sepsis) are also less likely.

If we can rule out primary water parameter issues and we don't have any potential vectors introducing disease (ie new plants, fish), then I am suspicious that you are seeing the declining water temperature impacting the fish. As the temperature drops, fish (especially the most sensitive ones or those with less mass:size ratio) will start to show adverse signs. This can include any with sub-clinical disease succumbing to these diseases, as the colder temperature will negatively affect the robustness of their immune system. Otherwise, even with healthy fish, we often see them linger at the surface since this is where the water is the warmest. We can also see depressed movement, bottom sitting in some (usually in later stages), appetite decline and anorexia (which if the temperature remains low they will stop eating and live off their body stores). This is obviously not ideal since natural over-wintering is hard on fish and often will cause some further mortalities.

Now this temperature is on the borderline, which is why I think only a few fish (those sensitive souls) are showing signs just now. Still I do want to cover overwintering for this pond since it'd be best to be intervening at this stage rather then waiting until the temperature plummets further. Therefore, if possible, we don't want to leave the fish to survive to the best of their ability. Instead, we want to step in and make things easier for him. To do so, we do have a few options; though which is most practical for your fish will depend on your situation, resources, and stocking density of fish. The common approaches we can take include relocating the fish to an indoor pond, set-up an indoor tank (either in the house or garage), heating the pond with a supplemental heat source, or using a combination of aeration and a de-icer to block the pond's ability to settle and eventually freeze.

 

Now the first two options are self- explanatory and as I have noted before the practicality of this will depend on your resources and the size/number of fish you are managing. This is often an option for smaller ponds or in cases where there fish stock are few or very small.

 

In regards XXXXX XXXXX a pond, this does typically require the investment of a installing a heating system. While this tends to be the most costly choice for keeping the pond warm over winter at least initially, it is a great option to keep the water temperature stable year round. And for parts of the world where these temperatures are common, this is a good investment to keep your winter fish losses as low as possible. The supplemental warmth will keep the fish comfortable, safe from the dangers of the cold and maintain a stable temperature (via heating) that can boost a fish immune system during this difficult time. As well, just to note, if you are modifying the water temperature to keep the pond warm during winter then the fish will be active as normal. This means they will have a normal rate of metabolism and therefore will have a normal requirement for nutrition and oxygen. As well, they will have a normal rate of waste production and therefore require the same level of care as they would in the warmer times of years. So, a heating system is a good option to keep koi activity as normal as possible, their lives as stable as possible, and avoid the serious stress this type of weather puts on their bodies. That all said, you can gently (specifically gently to avoid any quick change temperature shock) try supplementing the pond with warmer (treated) water at this stage to see if these signs respond and their behaviour normalizes.

 

Otherwise, while the weather isn’t quite cold enough yet for this, I do want to mention the de-icer/aerating option as well. This is where we allow the pond to react to the cold weather but in a controlled matter. By this I mean, allowing the pond to reach cooler temperatures but managing it to keep the pond as stable as possible and avoid a full freeze. To do this, the first step is to install an aerator or power head at the pond's surface. This will increase oxygen levels in the water but just as importantly it will keep the water moving, mixing and therefore harder to freeze. Further to this, we can install a de-icer to maintain the pond’s temperature ~40 °F. There are a range of de-icers on the market and you can see a comparison of these here (LINK). As well, here (LINK) is a wee video to give you an idea of how these are set-up and useful for our ponds.

 

Overall, with the lack of disease induced clinical signs and in the face of the declining temperatures, I would be quite suspicious that your fish are showing early stage cold stress. Therefore, while an autopsy of the deceased fish would be ideal to ensure there were no internal diseases we cannot see, I would say that it would be prudent to try to warm the pond at this stage and monitor the fish for normalization. If they respond, then you may want to choose one the above options to stabilize their water temperature and give them the best chance of surviving the winter.

I hope this information is helpful.

If you need any additional information, do not hesitate to ask!

All the best & happy holidays,

Dr. B.

-----------------------------------------------------------------------------------------------------------------

If you have any other questions, please ask me – I’ll be happy to respond. Please remember to rate my service once you have all the information you need. Thank you and happy holidays! : )

What Customers are Saying:

 
 
 
  • It was so professional, so personally concerned (as we were) and you answered all of our questions. George and I are so happy that I found ""JustAnswer"" on my Google search -- you are now in my ""Favorites"" list! And, yes we do love our kitty - she makes our life complete! Bev & George
< Previous | Next >
  • It was so professional, so personally concerned (as we were) and you answered all of our questions. George and I are so happy that I found ""JustAnswer"" on my Google search -- you are now in my ""Favorites"" list! And, yes we do love our kitty - she makes our life complete! Bev & George
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C.
  • This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!! Alex
  • Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult. GP
  • I couldn't be more satisfied! This is the site I will always come to when I need a second opinion. Justin
  • Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around. Esther
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C.
 
 
 

Meet The Experts:

 
 
 
  • Dr Scott Nimmo

    Dr Scott Nimmo

    Small Animal Veterinary Surgeon.

    Satisfied Customers:

    133
    BVMS, MRCVS. { Glasgow UK }
< Last | Next >
  • http://ww2.justanswer.com/uploads/VE/VetAnswers/2013-4-5_8257_prof10.64x64.jpg Dr Scott Nimmo's Avatar

    Dr Scott Nimmo

    Small Animal Veterinary Surgeon.

    Satisfied Customers:

    133
    BVMS, MRCVS. { Glasgow UK }
  • http://ww2.justanswer.com/uploads/VE/vetforyou/2012-6-20_33122_PearlPhoto.64x64.jpg Dr. Andy's Avatar

    Dr. Andy

    Medical Director

    Satisfied Customers:

    2570
    2003 Graduate
  • http://ww2.justanswer.com/uploads/AN/andrewDVM/2012-4-27_12585_iStock000011751407XSmall.64x64.jpg Dr. Drew's Avatar

    Dr. Drew

    Veterinarian

    Satisfied Customers:

    1840
    Small Animal Medicine and Surgery
  • http://ww2.justanswer.com/uploads/doggfone1/2009-07-16_133633_vet_pic.jpg Dr. Scott's Avatar

    Dr. Scott

    Veterinarian

    Satisfied Customers:

    865
    15 years of small animal, equine and pocket pet experience in medicine and surgery.
  • http://ww2.justanswer.com/uploads/DR/DrRalston/2011-10-18_1611_Vet.64x64.JPG DrRalston's Avatar

    DrRalston

    Veterinarian

    Satisfied Customers:

    169
    Over twelve years of internal medicine, surgery, and preventive care.
  • http://ww2.justanswer.com/uploads/VE/vetdeb/Debbie Headshot 500.64x64.jpg Dr. Deb's Avatar

    Dr. Deb

    Veterinarian

    Satisfied Customers:

    96
    I have been a practicing veterinarian for over 30 years.
  • http://ww2.justanswer.com/uploads/PE/petdoctor09/2011-12-14_51529_Picture1.64x64.jpg petdoctor09's Avatar

    petdoctor09

    Board Certified Veterinarian

    Satisfied Customers:

    72
    Veterinarian, General Practitioner
 
 
 

Related Vet Questions