View Full Version : Help! My Koi are dying!

Billy Boy
05-29-2014, 10:23 AM
I'm a beginner with aquaponics. I built my first IBC system in the early spring, cycled it, and stocked it with 25 2.5-3" koi about 2 weeks ago (5/16 to be exact).

When I received the koi, one of the 25 had already died in transit.

Water chemistry when I stocked was...

Ph = 7.4
Ammonia = 0ppm
Nitrite = 0ppm
Nitrate = 40ppm

After stocking, I got a little Nitrite spike... up to about 1ppm, but then it settled back down after a few days. My seedlings are growing and my fish are dying so now my water looks like this.

Ph = 7.4
Ammonia = 0
Nitrite = less than 0.25ppm
Nitrate = 10ppm

Water has remained clear the whole time.

After stocking I lost 3 more fish the next day. I figured it was transit related shock and that it would pass with time. But here I am am 2 weeks out and my koi are steadily dying a rate of about 1 per day.

They are also very skittish. They are not coming up to the surface to feed like I'm told they should. They prefer to hang out in the farthest most hidden corner of the tank all sitting together on the bottom. I have seen some eat occasionally when a food pellet passes close by, but they won't come out to eat.

I was concerned that my bell-siphon flush was too powerful and that was keeping them in a constant state of stress, so I have done a number of things to make that flow quite gentle, so I no longer think that is should be contributing to stress. I also added a big plastic tube to give them more places to hide. I figure it they want to hide, let them. But this has not made them any less skittish.

For the last few days I have been coming down in the morning to find an obviously sick fish. I have then scooped them up and transferred them to a make-shift hospital tank. First I tried a 6ppt salt solution, but that killed my fish within 12 hours. Next I tried a 3ppt salt solution on the next sick koi, but that has also led to death within 12 hours.

I now have another sick fish. Here are some pictures.


I'm not sure what else to do. Any suggestions would be greatly appreciated.

Clearly I'm going to need to restock with another batch of fish, but before I do, I really want to figure out how to keep the fish I have alive!



05-29-2014, 11:38 AM
I'm fairly new at all this too.

When you said that you cycle your system, was that with or with out fish?

As for the water return to your FT from your Bell Siphon...I have two 2" PVC returns one from each of my GB's. They dump about 150 gals of water in 3 minutes real hard and fast. The fish seem to love the fast moving water, they will swim against the current.

Do you have an air stone or lots or water retuning to the FT though an aerator ring?

Hopefully some of the more knowledgeable will be able to give you more insight.

05-29-2014, 12:53 PM
Wow, sorry to hear that.

There are other guys on here, that know a lot more then I about fish health. Hopefully one of them will chime in. I too, would of put them in a salt bath.

Just some random thoughts and questions...
Did you 'salt bath' them as soon as you got them ?

First I tried a 6ppt salt solution, but that killed my fish within 12 hours. Next I tried a 3ppt salt solution on the next sick koi, but that has also led to death within 12 hours.
They may have died with or with out the salt bath, anyway (?)
Are you leaving them in the high salt baths...or just for a short periods ...like an hour or less ?
Are you adding a lot of extra aireation to the salt bath ?

Billy Boy
05-29-2014, 02:10 PM
Yeah, I thought that the rush of water from the bell siphon would be a fun thing for the fish. Sounds like your fish are fine with a lot more sudden flow than I've got now.

On the question of fishless or fished cycling, it got a bit complex. I got the system cycled with a fishless cycle. Then I got a gold fish to make sure that things were cool. Then a raccoon got into my system and knocked over the GB feedpipe and drained all of the water out of my system killing my gold fish. I then re-established the cycle with the dead goldfish as an ammonia source. The goldfish had been dead for a good 2 weeks before I got the Koi.

I did not salt bath the Koi as soon as I got them. I just let the bag sit in the FT to let the temperatures equalize and then slowly mixed the tank water into the bag water and then I let them go in the FT.

I read that for ich, the salt treatment should be 12 hours in 6ppt salt bath, then 12 hours in 0ppt salt bath. Repeat 3 times and ich should be gone. I've read that salt bath is good for most other illnesses as well, so I just followed the ich instructions. After the first death I reduced to 3ppt salt for 12 hours. Second fish did not make it through the first 12 hours either.

Lots of aeration in the salt bath/hospital tank. Not a cycled system though. I was planning to change the water out every 12 hours, so I thought I might not need a filter... anyway, I don't have a filter on hand and it will take me a day or two to get one.

I'll check the chemistry in the hospital tank and see if it got too out of whack. Maybe that is what killed the sick fish?

I guess I could have introduced some sickness with the gold fish that didn't die completely with the 2 week no-live-host period. Also it could be that I got a batch of sick fish from the get-go. I got them from ebay seller "nextdaykoi". They have a very high rating and they have nice stuff (at least to my untrained eye). Still, the poor buggers got shipped from North Carolina to San Francisco, so that may have been just too much for them? I was planning to go with a different supplier next time if only to cut down on the travel distance.

As for aeration in the main FT... that was my first thought and I put a couple of stones in there to make sure there was enough oxygen in the water. The stones had no effect on the death rate or fish behavior that I was able to see. The system is an ebb&flow system with an 8 minute cycle and I've got a venturi air mixer on the GB feed pipe. Now the system has approximately 0.1 lbs of fish in it, so when I setup my hospital tank, I figured the the oxygenation in the FT was cool and the hospital tank was where the aeration was really needed, so I took the stones out of the FT and put them in the hospital tank.



05-29-2014, 10:01 PM
How hot does the water get during the day? Do you have a lot of air being pumped to the deepest part of your fish tank? My koi dive deep during hotter periods of the day. How much algae is in the tank that could be lowering the oxygen during the night? Could be a few things in combination.

Billy Boy
06-02-2014, 09:53 AM

I think the water temperature question was right on.

I'm in San Francisco and the temperature here is typically pretty mild and stable, so I guess I figured that with a "cold water" fish like carp, ambient temps would be fine. Clearly I was wrong! I got a thermometer yesterday.

We had a reasonably hot day for us, and at 4pm (about as hot as things would get I figure) the water temp was 64F. We had a not very cold night last night and this morning the water temp was 58F.

From my reading it seems that Koi typically like for things to stay above 59F and that water in the 70s is really ideal... so I've definitely been running cold. I was hoping not to have to heat my tank, but it looks like I'll have to bite the bullet.

I should be able to get the temp up and more stable pretty easily with a small heater. And I'll post results in a week or so.



06-03-2014, 09:07 PM
Years ago I was stationed at Travis. I guessed your temps were a bit closer to theirs (forgetting the cooling affect of the bay)

What are your water temps at the hottest part of the day? Are the fish stabilized yet or are they still having trouble?

06-04-2014, 12:55 PM
Could the problem be something in the water such as chloramine?

Billy Boy
06-13-2014, 07:59 AM

So things have stabilized. I got a heater and now I'm running an even 70F at all times. The 6 fish I still have appear to be much calmer and they has stopped dying.

Thanks guys for all your help.

I don't think that I have a chloramine issue. I've been treating for that with vitamin C when I add water, and because my ph is running high, I've been being generous with the vitamin C.

I've done some more reading on the subject of koi and temperatures and it seems that they have 2 different immune systems. A cold water immune system which is non-adaptive and a warm water immune system which is able to adapt to pathogens and is much much more effective at beating disease. It seems that it is about 58F where the warm water immune system switches on or off, and I was dancing back and forth across that temp virtually every day. Perhaps that was the issue?

Anyway, now I've got a system that is running with almost no fish in it, and so the ammonia is not keeping up with the plants.

Ph = 8.0 (trying to bring this down slowly)
Ammonia = 0ppm
Nitrite = 0ppm
Nitrate = 0ppm

Ph clearly too high. I don't know why it has creeped up? Perhaps they warmer water? I also noticed that it started to fall as the bacterial colony grew. I expect that with so little activity in the tank, the bacteria are starting to die off and this may be why the ph is climbing again?

So, it seems like I ought to get some more fish... but I am weary.

Even though the fish I have are not dying anymore, I'm not confident that they are not just super tough carriers of some disease cocktail. This experience has made me aware of the idea of a hospital/quarantine tank, but at this point I'm not 100% sure what I would be quarantining from what... am I protecting the old fish from the new fish, or the new fish from the old fish?

Also, what is proper quarantine method? On one side, I'm tempted to start an entirely new system and cycle it for my new fish, so that I will know that what ever pathogens they have are the ones they came with. Of course, the advice for cycling a system is to take some media from an already cycled system... so there is a cross contamination. On the other side, the new and old fish are all supposed to live together in the end, and the old fish are still pretty small, so what is the quarantine really going to do? Also, if I don't get a bigger ammonia source into my first tank soon, then I figure I'll start loosing my plants.

I'm not really sure how best to move forward from here. Got any suggestions?



06-15-2014, 01:43 AM
How many fish do you have currently? As for quarantining usually it's protecting old from New.

Aloha Don
01-01-2015, 02:31 PM
Please update your findings
Fish still dying or have you fixed the issue?
What was the issue????
Thank you