Help with dead koi

[Mmathis]

I’m so sorry to hear about your loss! Agree that we need lots more information about your pond. It is odd that all of your fish would die suddenly, after such a long time, but it’s impossible to give advice without any facts to go on.

 

[daffy]

4 other fish in pond about 5 months old fine. Very sad.

I am in nw NJ, also have a pond 12+ yrs. My koi were same age, over 12in. 6 koi + 16 goldfish. 4 koi died 2wks ago, all goldfish are fine. The pond is approx. 750gal. 28in deep, Was cleaning out leaves when I found the 2 largest koi on the bottom. Over the summer, they had eaten a large waterlilly but nothing else unusual. Do not know why, after these years , they died.

 

[MIKES KOI]

sorry to hear this; it could be a thousand things, ill try to narrow it down the best i can. do you test the water on a regular basis? if so whats the readings? did you add water? its cold here whats the temp there.eating or pulling up a lilly wont kill fish . did you notice the fish at the water falls and wont budge? did you notice fish flashing? do you feed ? do you stop feeding when water temps reach 50 ?is or was the pond covered in ice before you saw this?

 

[mrsclem]

750 gallon is too small for koi. They have grown over the years and probably outgrown your filtration. If you test your pond water, can you post results?

 

[MIKES KOI]

the post above is true, if the water was tested on a regular basis this would tell you fast. it does sound like a HEAVY load. but you never know , unless you test. if the water was good it will narrow it down.