my Koi all died..................

[Christine]

Hi everyone,
I'm new here, and I have a question for you all. My two beautiful Koi that I've had for a year were both dead this morning! Yesterday we lost our power due to thunderstorms. The power was off from around 2:00 P.M. until 5:00 A.M. Could my fish have died due to lack of oxygen?
There were two of them, and we've had power outages before with no fish loss. All of my goldfish are in another pond, and they are all still fine. The Koi were happy and healthy when I fed them yesterday evening. ANY "insight" would be greatly appreciated. I don't want to get more Koi if I have to be afraid of this happening again.

[CarolinaGirl]

Im sorry for your loss.

Yes...koi can die from lack of oxygen, but it depends on several factors. How big is your pond and how warm is the water? Did you have more fish in there, or were these the only two? How big were they? Did you have rocks in the bottom of the pond? Notice any strange "rotten egg" type odor?

[HEADACHE6]

Sorry You lost some fish , that always stinks .

As already asked , Any other fish in the pond that you lost fish in ?

One other thing , next time you lose power , don't feed your fish until it is back on for an hour or two , maybe even wait until the next day .

Again Sorry .

[PapaBear]

Another contributing factor would be the time frame of the power outage I'm betting (just guessing mind you) that you have plants, etc... in the pond to assist in your filtration. ALL plants consume oxygen once the sun goes down, so without any external source of aeration the pond would easily become oxygen depleted unless it was very, VERY large. Add to that the fact that you fed them, (which increases the oxygen depletion due to increased biological activity) and you have a bad situation on your hands.

[Christine]

These were the only two fish in that pond. There are a few plants in pots that sit on ledges around the pond. No plants down in the water.
The two koi were about 12-15 inches long. The pond is not real big. 275 gallons, 3 feet deep at the deepest point, and a surface area of 4'X6'.
I just can't believe those poor fish died like that. I have one big, flat rock that sits on two other rocks for the fish to hide under in the water. There was no foul odor at all. The water looked kind of "thick", and bubbly on top, tho. I did a test for nitrates, and all of that stuff. It tested good.
Like I said, we've had power outages before............for even longer periods of time. But, I guess it could have just been too much for them this time. And, I didn't think about feeding them being dangerous with no aeration.
Again, thanks for the answers.

[rainblood]

2 15" koi in 275 gallons? Oxygen depletion was probably the cause. The thick bubbly stuff is excess protien or DOCs. What kind of filtration did you have? Sorry for your loss

[lypope]

I'm sorry for your loss; it's always heartbreaking to lose a pet. It's more than probable that they died from lack of oxygen - that's nowhere near enough water for koi that size (or koi at all, except perhaps for fry.) You also said that there were thunderstorms that caused the outage - it's also possible that lightning (electrocution) was the cause.

[MikeM]

Koi that size in so little water can readily succumb to oxygen depletion over that many hours. There was no margin of safety that would allow them to suffer through the episide. This exemplifies my comment to many that koi do not grow to fit the size of a pond. They grow to be too large for the pond, and then they die. ....Unless it is a large pond with low stocking.

[kntry]

You also don't have much surface area for oxygen/gas exchange.

In the past when you had power outages, the koi were probably much smaller. You should have a minimum of 500 gallons per koi.

I'm sorry you lost your koi. It's always hard but you've learned from it so you can improve the situation. If you're going to keep the pond that size, keep goldies. They will do fine in that pond.

[UP ALL NIGHT!!]

Hi Cristine, You did not see them gasping at the surface of the water?
That's a shame. What an awful way to die.
I would have been out there bailing and dumping water. So sorry for your little ones.