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Strange fish death that looks like ammonia poisioning


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  • Regular Member

Hey all

I recently moved into a house that came with a large outdoor pond. It contained about 12 medium sized goldfish, I brought along 3 smaller goldfish who moved in with them.

All good for two months until my smallest one suddenly died (everyone else seems fine).Symptoms were that he became lethargic and then suddenly died after a couple of days. He also had black marks (see photos).

I've been fish keeping for a while so I immediately tested the water thinking an ammonia spike, this is what I got:

ammonia 0 (This wasn't totally a bright yellow like the card but I compared to tap water and we use prime. quite sure it is 0)

nitrites 0

nitrates 10-20

ph 7.5-8

So I'm at a bit of a loss on this one. Pond has decent filtration and oxygen flow. I also only feed every two days sparingly. I ran the ammonia test so many times and it just turned up nothing.

Any thoughts? I really don't want to see my other fish get sick :(

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  • Helper

That is tough to tell just by looking, could be any number of factors, including just a less robust fish in general. Is the behavior of everyone else in the pond otherwise normal?

 

It is spring and and the mark on his flank looks like an injury, more than a burn. Healing spots often turn black before changing back to their normal color, including with ammonia. But other things can cause that sort of mark too, and I’d guess it could even be a marine injuring that the fish was too week to fully recover from.

For a pond your nitrates are a bit high. Some terrestrial planes like bamboo will help utilize that, but otherwise just keep an eye on everyone’s appetites and behavior. And if the pond is above 60f please feel free to feed daily here this time of year. Every two days is a bit scant for their more active season.

 

If anything else happens please use this thread to respond and @ me so I see it :)

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Thanks @Arctic Mama, appreciate you helping me with an unpleasant topic (I don't feel great about it).

I think you might be right on the weaker fish / injury theory (he was the beloved runt). As the pond water has been clearing, I've noticed various old ornaments etc down the bottom so maybe an accident happened (I'll have to inspect them)

Behaviorally the other fish all seem fine and active. Visual inspection is trickier due to algae and blue water dye (from previous owner) but a couple I have netted look healthy.

Other suggestions I've heard are some kind of general infection or black spot disease/parasite. The latter (from what I've read though) doesn't seem exceptionally deadly and quite rare. I was considering using Praziquantel but I'm hesitant to unnecessarily medicate... (and for some reason, I've never had success with medications for many issues anyway).

Nitrates are something I'll certainly get down, this is a 800 litre pond in an undercover area.... So the cover combined with blue water dye has probably stunted algae growth. The previous owner only did yearly cleans so I'm doing regular top offs and smaller water changes to prevent a shock to existing fish.

We're also heading into colder weather here but I'll certainly feed em more when temps rise as suggested.

I guess I'll try to monitor and clean a bit before taking more drastic action with the other fish. Was just wondering if I should act in a more aggressive manner to prevent harm to the other fish.

Thanks for reading my wall of text, just care about the fish (always throws me through the loop when I lose one but I can't leave the hobby for some reason!)

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Definitely definitely do two or three rounds of prazi every spring. Gill flukes proliferate with the warmer weather and that is part of prophylactic maintenance for sure. If you need help with the prazi just tell me whether it is liquid or power and we can assist.

 

With those old ornament double check they’re not hollow, those can fill with souring, waste-laden water and really mess with the water quality. Syphoning down there to get up mulm and debris is also something you want to do monthly, at least. Every bit of waste that’s taken out of the pond is one less thing to rot and deteriorate :)

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@Arctic Mama

Oh ok! I didn't realise this was part of standard prophylactic maintenance. Are there any other medications I should dose into the pond?

As mentioned, here in Australia we're entering winter so our pond is down to about 50f and decreasing. Guess there isn't a rush on the prazi now but I'll get it sorted. The last owner certainly would have never done any fluke control etc.

Guess I'll need to spend the weekend working out the pond water volume for medication.... last owner says 800ltr but that is a rough measure argh.

I'll get onto the ornaments etc too, thank you so much for your help.

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If you’re heading into winter you’re okay - I was thinking northern hemisphere 😂 cutting back on food is fine, then! When it begins to warm up definitely acquire some powdered praziquantel and we will do some maintenance rounds then. That’s the only prophylactic medication we recommend here outside of the initial purchase quarantine.

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@Arctic Mama

So a bit of an update.

Fish still behaving fine but I've noticed my largest goldfish (an original in the pond) has basically the same kind of mark on his side.

Ammonia is still 0 so now I'm leaning towards some sort of parasite. When my wife gets home tonight, I'm going to try a partial water change and start a course of prazi.

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Sounds good, if the weather is cold run then prazi on the longer side, two weeks in, one week out with a big water change between.

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Do you think a salt bath on the fish would be worthwhile?

I'm a little skeptical, I guess the medications are enough and I don't want to stress him.

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No don’t bother. If you’re going to take him out again or do treatments that aren’t pond-wide I’m going to recommend buying an inexpensive microscope and take a scraping so we can see what we are actually dealing with. If we are. They’re not very expensive and absolutely worth it when you considering the impact of trying to deal with parasites in a whole pond.

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No worries, thanks again for all your help (I haven't had much luck elsewhere).

Sounds like a clean and prazi is the natural next step so I'll go that way and then get the scientific equipment if things dont improve.

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Check in as needed, we’re here. I think I got my microscope for $4O on Amazon and another few bucks for slides and stain, well worth it when you’re considering the cost of medicating a whole pond if the prazi won’t do it. But flukes are so common and flashing is absolutely a symptom, so let’s start there :)

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No worries, will do and thanks again for the advice.

So far no changes or developments to report.

I've done the following:

  • Checked for dangerous ornaments (nothing found). Removed a few random marbles and junk I found though!
  • Two quarter water changes with Prime water conditioner.
  • Dosed Praziquantel using the bottle's instructions.
    We've completed the first phase where it advises to full dose and then do a quarter water change after 48 hours. Then we have another dose to do in a bit under a week so I imagine the dose is pretty good / long considering directions.

So far big red still has the black mark but its only been about 4 days since initial treatment (otherwise he seems fine). Maybe I'll get a photo but he is very smart/difficult to catch (its essentially the same as the small fish). Hopefully if it is a parasite, it is just dead and I need to wait for the black mark to clear up. Hard to tell as finding info about this condition is sparse.

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  • 1 month later...
  • Regular Member

Sorry it has been a while, I've had a few personal things going on but thought I'd share an update in case anyone was having similar issues.

Generally speaking, there isn't much to report.

So far, I haven't noticed any newly infected fish and there haven't been deaths. Big red (the one I believe is infected) still has the black mark but I think it has somewhat very slowly reduced and he is behaving fine (keeping a close eye on him). I'm hoping to see less of the mark as winter sets in.

Praziquantel treatment is finished now and the pond is getting below 10c so hopefully any parasite will be controlled. After the medication based water changes we're seeing:

0 for Ammonia, Nitrites and Nitrates

7-8 for Ph

Despite 0 Nitrates, I believe the pond is still cycled as it has plenty of algae that is probably eating residual nitrates after our medication water changes. We also haven't gone too hard on water changes as we wanted to let the last course of Praziquantel stay in the pond.

As a side note, I've also noticed small birds visiting our pond so I suspect this might be how the parasite got into the pond.

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Oh yes a bird could potentially spread something into there. The downside is that would most likely be viral and beyond our ability to treat except addressing symptoms and overall water quality and stress. Giving his immune system the best chance possible, essentially. Glad things aren't getting worse! The params look great and yes, algae would keep nitrates way down, as do terrestrial plants :)

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