Don’t Feed Your Fish In Cold Water!

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I noticed a fairly common but disturbing post on a pond forum today and I wanted to share this with you here in the hopes that it will help you avoid this with your Koi in particular.

Here’s the post

This is a story that would usually start with “A friend of mine…” but I’ll fess up.  I made a major bone-head mistake and fed my koi while the water was still too cold.  The weather was warm and they were obviously very hungry, but I didn’t think to check the water temperature.  Now I have some very sick koi, including two that are near dead.  They’re behaving strangly, some are losing scales, and a few even have blood streaks in their fins.

They’ve always been very healthy, and all of my goldfish appear unaffected, so I was baffled.  After testing the water (all normal levels) and some serious googling I think it’s septicemia caused by the food rotting in their digestive tracts.  I’m now trying to warm up the pond and running to the store for some salt.  Any other recommendations for this emergency case?  As always, thanks in advance!

You can read the follow up here.

The real lesson here is that you simply don’t want to feed your fish, and particularly Koi in water temperatures that are below 50 degrees F.  It’s not that they won’t eat, because as you can see, they’ll consume food voraciously, but whether they’ll be able to successfully digest this food is another thing altogether.  And if they cannot, you’ll probably run into some major problems.

I’m not sure if there is a good answer for a solution here.  Warming the water may help with a bit of time, but whether that’s enough to curb the losses and suffering is still questionable to me.  If you see skin problems and wounds, it might make sense to add salt but this isn’t always the answer to skin issues in every case.

As I’ve often said, I don’t consider myself to be an expert on fish health but I do know people that are.  Whenever you run into problems with your fish, be sure to stop by and there’s a good chance you’ll get some useful advice that will help your fish.

And it probably goes without saying that prevention is the best remedy in almost every case.  We do certainly learn from our mistakes and those can’t always be avoided, but sharing experiences just might help someone else avoid the same fate.

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3 thoughts on “Don’t Feed Your Fish In Cold Water!”

  1. I live in an area where the temps are below 50 degrees for 5 to 6 months… snow, ice etc. on my pond. I have over 30 goldfish, some 8 years old. I get very nervous at this time of the year when they are active yet this article says feeding in water temps lower that 50 could cause them much distress or kill them . How can anything living go so long – 5 to 6 months without eating?

  2. Thank you for this question. I think something can be gleaned from the forum post mentioned in the article. You’ll note that the goldfish appeared to be fine, but the koi were not. So first it’s apparent that some fish deal with cold water feeding better than others. So the two main variables are the type of fish and the water temp. Most fish will slow down in cold water but as spring comes in you can certainly watch them and try to gauge by their activity level if their metabolisms are ramping up…that would be one sign. But also, I often suggest people get to know other pond folks in their area…koi clubs, water garden clubs, and such. The folks who have spent year after year managing ponds in your area are the best source of knowledge you can find. If you follow their lead and model what they do (successfully) you’ll most likely be just fine. Spring time can be sort of a feel out process here but between watching the temps and not feeding when it’s obviously well and consistently below 45 to 50F. then you will likely avoid any big problems. All the best to you!

  3. Great points, like bears and a few other critters, some fish go into a deep swimming, slow moving type of hibernation statues as the temperature of the water drops so I don’t normally feel my fish between November and late March or early April here in the mid west.

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