Nitrite poisoning? Help.....!

[Isis]

Hi there,

I am having a problem with my pond, or rather the fish in my pond. My dear, dear fish. I have already lost two this week - both of them much smaller than the other fish in the pond - and more recent additions than the others. I have moved recently and the pond is only 5 months old. It's a liner pond, with no bottom drain (it is a temporary measure and am planning a proper pond). I had a single biological filter running with an 8watt UV bulb, which was insufficient, when I noticed the fish not looking to happy I put in another filter with a 15 watt UV light (this has only been going a week). I have two submersible pumps running the filters. I have 9 40cm koi in a 20 000l pond.

Fish behaviour - they are listless, they hang at the surface, sometimes head down, one of them breaks the surface quite regularly and seems to take a big dose of air. I inspected the gills of the dead fish and while their colour was not great, quite dark, aside from a little pond algae there doesn't seem to be any gill deterioration. One of the fish looks like it may have carp pox (small waxy swelling on mouth) and flukes toward the rear of the tail. I have a picture.

The most stressed fish have their back fins clamped (anal, ventral?) and are breathing fast. I have not fed since this started. Now for my water -

I did a 20% water change and used water conditioner half an hour ago and added a little salt and the water is as follows:

Ammonia - less than 1.2 but not 0
Nitrite - 0.3
Nitrate - 10
Ph - 7.5
General hardness - 60
Carbon hardness - 60

If anyone out there could please give me some advice on the best course of action before I lose more fish I would be eternally grateful.

Isis

[CarolinaGirl]

Get your salt levels up to .3% ASAP to prevent brown blood disease (note....this is NOT 3%....it is .3%). Dont' do this slowly....get that salt in there now. You can use Solar salt from Lowes if you need to....the stuff in the blue bag not the yellow bag. Brown blood disease from nitrite poisoning will kill them quick. Get some ammonia binder in there too. Figure out why you had an ammonia spike in the first place. Inadequate filter? Too many fish? Too much food? You really need to examine the system and figure out what happened so you can prevent it from happening again.

[Erns]

You don't mention that you have an airpump in there? If not get a good one with a couple of airstones. Try to dertermine your turnover rate, 20 000l of water is a lot to filter once poluted. You should be turning over the whole pond at least once every two hours. Try to add something to boost your biofilters. Do small regular water changes. Have a scrape done and check for parasites that might invest the gills like gill flukes? AND add that salt ASAP.

There is really a lot that could be going wrong in a new temporary system like yours.

[CarolinaGirl]

Also, the parasites you can see on the fish are not flukes. Flukes can only be seen with a microscope. they are probably either fish lice or anchor worms which can be controlled with Dimilin. The carp pox is nothing to worry about...it goes away when the water warms up.

Breaking the surface of the water is known as "Breaching" and is the fish's attempt to get more air into his gills. I have a fish that has done this ever since I had her and she is fine....probably just old gill damage from before I got her. but if your fish never did it in the past and now it is, then it is a problem. The fish is trying to get more air because her gills are compromised.

[dick benbow]

As I re-read the initial post, to again understand what facilities we were dealing with, it struck me that the nitrates were very high and that a 20% water change would have dealt with it. Except with no bottom drain, I'm afraid the fish ( and those trying to help solve the situation ) are dealing with something less than pristine conditions of water along the bottom. While we're making recomendations to help we need to be reassured that the water
along the bottom is being directly targeted for removal or the water changes will not have the impact needed to arrest the situation. Of course the eventual cure will be to place a bottom drain(s) in the liner and to get information on the type or filter and turnover rate. But for now, in order to stop the bleeding, we need to know that the water replacement effort is being done correctly. During water changes the salt levels will need to be monitored and re-adjusted back to recomended levels.

[schildkoi]

.1% salinity is enough to handle the nitrites as it relates to BBD. In addiion, this lower level will not complicate efforts on parasitic treatments.

Steve

[Isis]

Both my pumps are at the bottom of the pond and so I would assume that this is the water being targeted for removal during water changes. I don't have a test here to accurately measure the amount of salt I need to add - is there any recommendation per litre I could add? I just put 2kgs of coarse sea salt into the pond. I usually use a fair amount of salt, but I've been concerned about Ph so have been sparing with it in the last week or so.

The water change seemed to make little difference to the nitrite level.

[Isis]

In addition to the two submersible pumps I also have a smaller pump with an airstone going.


Not all the fish seem affected - but today I noticed more of them seem lethargic or are breathing hard. I noticed a lot of algae died back a couple of weeks ago - I was scooping it off the top of the pond everyday at about midday and into the afternoon.

[Isis]

Does 50kg of salt for 20 00 litres sound unreasonable?

[saratogatan]

"20 00" L ? If it is 20000L, you need 20Kg to bring salinity up by 0.1%.

Make sure that the salt is 'Solar salt' or one without any additive.

stan