Death of fish help identify the causes.

So first of all this is a minor autopsy with pictures to try and identify the cause. Yes a bit gross but I felt necessary and he was dead anyway.

Secondly had a few tanks, freshwater, this is a huge 7/800L no where near overcrowded about 20 small fish 1 roughly 10" common plec. Filter is perfect water changes regularly with RO. All tests show good (and have been since setup) for the usual ammonia, no2, no3, pH, and phosphate. All other fish look happy and healthy.

Fish in question, largest of 4, black widow tetra. Been breathing heavy for some time stopped eating couple days, dead today. Treated for bacteria at a guess and added some aquarium salt as per the instructions to try and help.

I suspected Gill disease or flukes so I checked his gills before burial pics below look dark to me can't see flukes but I would like ideas, some dark patches on the body not sure if related. Was about 18months old. Obviously like to treat if a issue to preserve the others health. Maybe I'm overthinking and it was just his time?

I did post in your welcome post. You say you are using ro water for water changes. Is this being mixed back in with tap water or something else?

If not then RO water by itself is what's probably killing your fish. It has no mineral content and therefore no buffer capacity or water hardness. As such the PH will swing all over the place based on what dissolved gasses are in the water at the time (which is constantly changing).

brutal!

Yeah, Imma have to agree with @CaptainBarnicles, you shouldn't have added the photos

Safecookie said:

So first of all this is a minor autopsy with pictures to try and identify the cause. Yes a bit gross but I felt necessary and he was dead anyway.

Secondly had a few tanks, freshwater, this is a huge 7/800L no where near overcrowded about 20 small fish 1 roughly 10" common plec. Filter is perfect water changes regularly with RO. All tests show good (and have been since setup) for the usual ammonia, no2, no3, pH, and phosphate. All other fish look happy and healthy.

Fish in question, largest of 4, black widow tetra. Been breathing heavy for some time stopped eating couple days, dead today. Treated for bacteria at a guess and added some aquarium salt as per the instructions to try and help.

I suspected Gill disease or flukes so I checked his gills before burial pics below look dark to me can't see flukes but I would like ideas, some dark patches on the body not sure if related. Was about 18months old. Obviously like to treat if a issue to preserve the others health. Maybe I'm overthinking and it was just his time?


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Did you come to any conclusions as to cause of death? I don’t know anything about this. Did you isolate the ailing individual? Hope the others are ok.

Anonymous Fox said:

Yeah, Imma have to agree with @CaptainBarnicles, you shouldn't have added the photos

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The photos didn’t bother me. Ones of a mammal or bird, unless extreme closeups, would have been disturbing. I’ve known piers & wharves & fishers, so hardly shocking images, & possibly of clinical value.

xxBarneyxx said:

I did post in your welcome post. You say you are using ro water for water changes. Is this being mixed back in with tap water or something else?

If not then RO water by itself is what's probably killing your fish. It has no mineral content and therefore no buffer capacity or water hardness. As such the PH will swing all over the place based on what dissolved gasses are in the water at the time (which is constantly changing).

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The ro isn't completely pure I oversized the membrane and the pump pushes through at decent pressure with a solenoid valve controlling the reject water I do monitor the water tds at point of storage before being put through the water change cycle. The water here is pretty poor around 250-280 tds and after the filters around 30 then the last hour or so after the pumps and reject switch off it climbs back upto 80 I reckon a average around 50, obviously the pre filters take alot of the poor content out and most of the chlorine and chlorides. It's been running for a couple of years like this and been a steady pH every time I've tested it at 7.8 which is consisistant with reading pre ro install. The reason I installed this was phosphate spike causing a blue green algae to take hold so I monitor that too and hasn't moved from 0.5ppm since. Due to the size of the tank it keeps all test readings stable. All other fish have no signs of disease.

JennySolano said:

Did you come to any conclusions as to cause of death? I don’t know anything about this. Did you isolate the ailing individual? Hope the others are ok.

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Others are all OK it may of been stress due to the social environment always do a multitude of tests if anything looks off water quality is fine.

Have you tested your GH and KH just to make sure? You say it's been running like that for a couple of years so it probably isn't the issue but if it was me I would do a double check on the GH/KH to rule it out.

Anonymous Fox said:

Yeah, Imma have to agree with @CaptainBarnicles, you shouldn't have added the photos

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Yes I didn't enjoy it but how else can you investigate. I hoped someone could identify if this was Gill bacteria or flukes. I did state this in the first sentence for those not wanting to read on.

I wouldn't know what to look for hope you find some answers

Anonymous Fox said:

Yeah, Imma have to agree with @CaptainBarnicles, you shouldn't have added the photos

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The photos may be useful to someone who knows what they're looking for....but 'orrible!

xxBarneyxx said:

Have you tested your GH and KH just to make sure? You say it's been running like that for a couple of years so it probably isn't the issue but if it was me I would do a double check on the GH/KH to rule it out.

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Thanks for the advice I have just rerun the pH and a kh test. The api test always ready 7.8 (I use the high range) I tried with a diffrent brand tester which shows 7.4 but that's the difference in the tests. Api has always been the light brown. Kh hasn't been run since I pre ro that reading is shown with a - todays with a * the reading 5.4 dkh what looks better than before and in the middle of the range I've double checked is reccomend. But I would value your thoughts here looks all good to me.

CaptainBarnicles said:

The photos may be useful to someone who knows what they're looking for....but 'orrible!

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That's was the idea. I wasn't making sushi, the gills are layered it was merely opening them to see with a pointy impliment, and pointing to dark patches. He's been buried in a ornate garden. Not flushed down the toilet.

Safecookie said:

That's was the idea. I wasn't making sushi, the gills are layered it was merely opening them to see with a pointy impliment, and pointing to dark patches. He's been buried in a ornate garden. Not flushed down the toilet.

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Respect to you for trying, rather than simply stating it died from Whatever Disease, or blaming inbreeding and/or mysterious viruses.