Dead Koi and the rest not active

[nancyp]

I have a 900 gal pond, started last August. Since a heron attack about a month ago, my white koi has been acting strange, very scared - I don't blame him- wouldn't come up to eat and was inactive. Yesterday he seemed to be up near the surface at least, which I thought was good. He has not really been eating good at all. Now today, he's dead. I do not see anything wrong at all with his body. Tests on the water remain good, please verify that they are good.
Ph 7.4
Ammonia 0
Nitrite 0
Nitrate 0

The few remaining fish have really not been eating either, and they stay huddled together, not swimming around, not active. I thought it was because of this one being so scared, that he convinced them to stay hidden. I also had a dead one last Friday, but he had a missing eye, so I thought that caused his demise.
I have a milk crate down in there, which they stay hidden under most of the day. I don't know what is going on with them.
Here are some pics of the dearly departed. Best I could do. Any ideas?

 

[capewind]

Awww, sorry you lost this guy. Without something obvious on the fish, I have no idea other then to suggest you test your KH to rule that out....

 

[sissy]

That looks like a female too .I usually keep my ph at 9 .What about oxygen .

 

[nancyp]

Since I wrote this morning, another one bit the dust. Again no sign of anything wrong with the body, at least to my eye. Just that he was very slowly swimming around at the surface this morning. No gulping for air.. just staying still or slowly moving. I took a water sample to my pond store, which verified that there is nothing wrong with my readings, and the fish had no sign of anything unusual. They sold me some ICK-Out solution to put in my pond. The guy said it will treat more diseases that just Ick. I don't know.. the label doesn't say that. I put it in there. We'll see.
So far, the last two remaining Koi are acting fine... but we'll see.

 

[sissy]

Does your filter look like it is running right .Is your pump ok and not electrocuting your fish .Even the slightest shock will kill a fih .Did anything wash into the pond that your test kit is not picking up .I know we have had some heavy rains here

 

[nancyp]

We had heavy rains here too, but there is nothing to wash in there. I don't use fertilizer, bug killer, weed spray or anything at all in my yard. The filter and pump seem to be normal. The two remaining fish seem to be fine so far, although they do not eat any of the food I give them. I do see them picking around at the hyacinths. They are tiny fish - about 3-4 inches, so I am keeping my fingers crossed for them.

 

[nancyp]

Well, I am down to one fish now. And I am sure he will not last long. He has not eaten in days and is very lethargic, just like the others were. I have the ich treatment in the water now for more than 2 weeks. The pond guy said to add it again after 3 weeks, and then again in 3 more weeks. I sure hope that it is gone at that point. My pond looks so pretty now. Even my lily is getting a flower, but the fish die.

 

[dieselplower]

That's sad. My suggestion would be to remove the Koi from the pond and put it in a smaller container with fresh water where it can be more easily treated. treated for what, I don't know. There are other sites where very knowledgeable members will help you figure it out very quickly.

 

[addy1]

Darn sorry Nancypl
Before you put more fish in you might want to swap out the water, let the pond cycle fishless for a while. IF you are not stuck on koi, go to some of the real pretty shubunkins, gf, they are a lot hardier.

If you want to stick with koi, let the water sit, then start with one see how it does.