What kind of permanent demage nitrite can cause?

[SimonW]

Hello friends:

Something went wrong with my water (most likely nitrite shock) which led to that 3 out of 50 koi died and 2 lost their ability to swim normally: They cannot keep balance and swim like loaches. It happened 2 weeks ago and I seem to see some improvement, but I am not sure.

I wonder if anyone more experienced here could describe sequelae of nitrite damage in the surviving koi? Thanks!

[coolwon]

How is your KH, maybe the bio-filter has taken a knock due to overstocking ?

[SimonW]

How is your KH, maybe the bio-filter has taken a knock due to overstocking ?

Thank you for your concerning!

KH was not so high, 50-80 ppm. But I don´t think that was the cause.

This happened when I was moving out the fish from indoor over-wintering tanks to the out-door pond. I did not moved out the active biofilters directly but with some days in-between (lack of time).

Anyway, the koi somehow suffered from water quality issue, and my best guess was nitrite spike. Usually I would add quite some NaCl, but this time I might have not added enough, because I wanted to use the waste water to my plants, and high salinity is not good for them.

Another possibility is the salt I used. Earlier I used pure NaCl, but this time I used rock salt with anticaking agent E536 which is potassium ferrocyanid. Now I realize that this can be the problem, not nitrite. I did not care to find out what E536 is until now.

Anyway, I hope that these two affected koi will recover.

[BWG]

Looks like you went light on the salt and the E536 amount would be very small. Maybe something else is in play?

I once had the very same issues in a tank of small koi and it was from a submersible pump that had a electric leakage issue. No GFCI was connected to the pump to shut it off. Some of the koi never regained the ability to swim correctly. Several died.

[SimonW]

Update:

Thank you BWG for your reply. It could be. Now I am using another pump.

Since one week back I moved these 2 damaged koi swimming like loaches to a quarantine tank with pristine water. One of them still swim like a loach, but looks healthy, no skin damage. The other now swim normally, but had a slightly red, inflammatory area with skin now seemingly peering off and the redness having turned darker, no ulcer or slim-coat. This redness can be caused by scraping itself to a rock (some rocks in the pond).

I did scrapings for 1 week ago and I did not find any parasites, and I have also treated them and the pond with PP, so I am quite sure that it is not caused by parasites.

[kdh]

always check the gills

[Tanyaclick]

Did you condition the new water?

[SimonW]

Did you condition the new water?

What do you mean with conditioning water? I usually add certain amount of NaCl and baking soda to new water, and that is all.

I am considering adding CaCl2 instead of NaCl.

[cindy]

If you have city water you need chloramine binder

[SimonW]

If you have city water you need chloramine binder

Thanks, now I understand. Here we have very good water therefore no disinfection chemicals are added, that is what the tap water company told me. They only adjust the pH of the water with baking soda.

[NickK-UK]

Hello friends:

Something went wrong with my water (most likely nitrite shock) which led to that 3 out of 50 koi died and 2 lost their ability to swim normally: They cannot keep balance and swim like loaches. It happened 2 weeks ago and I seem to see some improvement, but I am not sure.

I wonder if anyone more experienced here could describe sequelae of nitrite damage in the surviving koi? Thanks!

Have a read of "Brown Blood disease".

The high nitrite levels cause the O2 capacity of the blood to drop, this causes the fish to come up for air on a regular basis. It also causes damage to their internal organs with prolonged exposure.

Next the high nitrite/nitrate causes the fish to be irratated and often the skin too. It's almost like they're anxious.

I have a bio-orientated pond where the plants have finished early this year plus they blocked some flow to the skimmer causing filtration not to remove detritus which mean that a water test a couple of nights ago showed zero ammonia but high nitrite and nitrate - the next day I did a 40% water change (around 6000 litres).

Today:


So today, they also seem alot happier, more relaxed without coming up for air in the extended time I took to observe them.

Agreed on the chlorine and chloromine binder. I always have some in reserve for emergencies.

Note the two females are/have been porky from the get go