Strange Koi Habit

[jay_elliott]

Over the past few weeks my 3 largest koi are almost exclusively staying under the waterfall in my backyard pond. I have not seen them do this for such an extended period of time.   I have had these fish since they were 3" and now they are about 15 years old.  Anyone experience this or anything similar? I am just boggled, the water quality is great (pH, ammonia, etc.).  Other than a hot summer here in New Jersey nothing else has changed.  The water temp in the pond is still hovering around 75 degrees. ?????????

[Kittyzee]

I don't have koi, but goldfish.  When mine do that (and it's usually when it gets hot and stays hot) I figure they want more oxygen or air.  The turbulence from the falls creates more air in the water--at least that's my take on it.  Maybe someone else will have a different reason....

[PondmaninAL]

LuAnn, you are probably right. Koi have a higher demand for air than goldfish.

[jay_elliott]

The odd thing is, it is only a few fish that congregate under the waterfall.  I have a total of about 50 fish (Koi, shebunkin, and goldfish).  Just very odd behavior.

[jay_elliott]

Unfortunately one the aforementioned koi died today . 19" beatiful golden and red colored koi.  Does anyone have any suggestions?  I still have two more koi that seem to be congregating under the waterfall only eating the little algae on the walls of the pond. I do not have a very good source for information in the area (quality pond or pet stores).  The rest of the koi and goldfish in the pond seem to be perfectly heathly, eating, swimming, etc.

Any help would be appreciated.

Thanks

[miguynmkoi]

Sorry about that.  I don't have a good answer for your koi's death.  I agree with LuAnn and Scott above, koi are more sensitive to change.  Did you look at the body to see if there was any infection, bugs, or anything? 

[JuneBug]

Sounds like low oxygen...are you using an air bubbler ? ...maybe test the water for oxygen (expensive meter- but not if your fish are dying)

[Kittyzee]

You say you have checked your water parameters and they are fine.  Have you added water recently and if you have--if you live in a city, you need to add dechlor or this could be a problem for your fish.  It sounds like they are needing more oxygen:  koi are much more sensitive to water conditions than goldfish. 

[trish]

I'm sorry for the loss of your koi.  The others are correct when they say that koi are more sensitive to water conditions than the hardier comets and shubies.  Usually when fish hang out underneath a waterfall it is a sign they need more aeration, but not always.  During the warmer months pond water heats up and holds less oxygen than cooler water.  If you have a lot of plants in your pond, it could also be contributing to less oxygen during the night.

How big is your pond to be able to hold 50 fish if you don't mind me asking?  Last time you did a water change?  Have you added any new fish that wasn't quarantined?  Have you added any chemicals ie; algae removers?  Also, what are your water parameter readings, specifically ammonia, nitrites, nitrates, KH, GH and pH?  Without knowing specifics it's only going to be a guessing game as to what "could" be wrong that caused the loss of an otherwise healthy and large koi.