Cory just died. Worried about others. Hope someone can help.

[AilyNC]

We looked at tank 8:30am. All seemed ok. Few mins later noticed very still, very pale looking Cory. I thought it was dead but it moved. I started setting up a hospital tank. The Cory was swimming erratically. Seemed to be twisting & turning. Then it died. By 9am.

I don't know what happened. Last night all seemed well in the tank. This morning I tested water

Ammonia 0
Nitrite 0
Nitrate 10

It's a 127L/34G tank heavily planted. Tank mates. Last new addition was 20th October, a replacement WCMM that died within 2hrs of being added to tank. Last water change was 25th.

Water changes with API Tap Water Conditioner. I added TNC root tabs on 25th. Also Sachem Flourish Comp (2.5mls). Also added 2.5mls Wormer as was noted here some barbs looked very thin when purchased & this would be good precaution. Last dose was 25th.

11 other Bronze Cory
9 White Cloud Mountain Minnows
10 Cherry Barb

This is a very very peaceful community tank. I'm so worried about my other fish. @Colin_T @NCaquatics @AdoraBelle Dearheart hope you can help

I find the video shows paleness best and has the swimming issue

And here's video of active tank mates just now

 

[Brendanpat]

Hi . I'm no expert as you know . That's why I'm waiting on them to advise .After I lost 12 fish that time ,I'm still not exactly sure what it was . I didn't have the test kit at the time .so thought it was ammonia spike ,then hand sanitizer and my latest theory was extra chlorine/chloramime in water due to pipe cleaning. My big pride and joy peppered corie was behaving like that last week .just lying there and then burst of swimming and tumbling. I thought it was hand sanitizer because I had to leave work and go home and collect 40 fry .I had changed water the night before aswell . But anyway I didn't do another water change . I just dosed the whole tank with the api water conditioner and thank god she was fine the next day .Hope the rest of yours are fine !

 

[CassCats]

Its plausible whatever the white cloud died from may have spread, I would do another water change asap

 

[Colin_T]

Did you quarantine the white clouds before adding them to the display tank?

The white in the dead fish could be microsporidian (muscle wasting disease) or something else.

The swimming at the end was simply a dying fish in it's last throws of life. It was in a bit of pain.

The other fish in the videos look fine.

I would monitor them and if any look pale or white under the skin, then add salt (2 heaped tablespoons per 20 litres). Keep salt in tank for 2-4 weeks. Until then, do a 75% water change and gravel clean the substrate every day for a week. This will dilute any disease organisms that might be in the water.

 

[Gypsum]

Poor wee guy. I've had corys do the same thing in otherwise (ostensibly) healthy and well-maintained tanks. In my case, I had other cory species who were fine. They start swimming erratically, just like that, and then drop dead, or I would euth it. Never looked pale, though. I had issues with Panda corys and C. trilineatus. When I was losing my trilineatus, slowly, over a period of a few months, both Byron here and Ian Fuller on Corydoras World suggested that some corys, especially fish that are mass produced for aquariums, may just be weak, poorly bred fish. I've since seen multiple other sources affirming that this is the case for Pandas.

Still, I spent a lot of time Googling and changed some of my tank maintenance practices. Haven't lost any corys to the spiralling death swims (knocks on wood) since, although the only 'mass produced' species I have now are C. pygmaeus. Anyway, no idea if you are already doing these or if it's useful.

I started doing 75% weekly water changes, instead of 30-50-ish.

Looked up Scottish Water and SEPA reports for Glasgow water, worked out that it is very clean, without much chlorine or chloramine, and we could lower the Seachem Prime dose. OH has a PhD in chemistry, so he has a pretty good understanding of this stuff and can read scientific reports.

I don't know if you use a Python or similar for water changes. We were pouring a capful of Prime directly into the tank as we filled it up. Found some reports on forums suggesting that if a fish ran into a high dose of that stuff, bad things could happen. Now we pour the Prime and the Flourish into a bucket of water and then pour that into the tank.

I read somewhere that if there's any buildup of harmful stuff on the substrate, or if there are dead spots in the tank where there isn't enough oxygenation, corys can have problems. Now I'm running powerheads in all the tanks that have catfish. They certainly won't hurt.

 

[AilyNC]

Did you quarantine the white clouds before adding them to the display tank?

The white in the dead fish could be microsporidian (muscle wasting disease) or something else.

The swimming at the end was simply a dying fish in it's last throws of life. It was in a bit of pain.

The other fish in the videos look fine.

I would monitor them and if any look pale or white under the skin, then add salt (2 heaped tablespoons per 20 litres). Keep salt in tank for 2-4 weeks. Until then, do a 75% water change and gravel clean the substrate every day for a week. This will dilute any disease organisms that might be in the water.

It's just one WCMM that I added. He died within 2 hrs, was taken out, water change done, then another on Sunday.

I'll do another change today once I get toddler to nap (within the hour). And keep on those for a week as recommended.

 

[AilyNC]

Poor wee guy. I've had corys do the same thing in otherwise (ostensibly) healthy and well-maintained tanks. In my case, I had other cory species who were fine. They start swimming erratically, just like that, and then drop dead, or I would euth it. Never looked pale, though. I had issues with Panda corys and C. trilineatus. When I was losing my trilineatus, slowly, over a period of a few months, both Byron here and Ian Fuller on Corydoras World suggested that some corys, especially fish that are mass produced for aquariums, may just be weak, poorly bred fish. I've since seen multiple other sources affirming that this is the case for Pandas.

Still, I spent a lot of time Googling and changed some of my tank maintenance practices. Haven't lost any corys to the spiralling death swims (knocks on wood) since, although the only 'mass produced' species I have now are C. pygmaeus. Anyway, no idea if you are already doing these or if it's useful.

I started doing 75% weekly water changes, instead of 30-50-ish.

Looked up Scottish Water and SEPA reports for Glasgow water, worked out that it is very clean, without much chlorine or chloramine, and we could lower the Seachem Prime dose. OH has a PhD in chemistry, so he has a pretty good understanding of this stuff and can read scientific reports.

I don't know if you use a Python or similar for water changes. We were pouring a capful of Prime directly into the tank as we filled it up. Found some reports on forums suggesting that if a fish ran into a high dose of that stuff, bad things could happen. Now we pour the Prime and the Flourish into a bucket of water and then pour that into the tank.

I read somewhere that if there's any buildup of harmful stuff on the substrate, or if there are dead spots in the tank where there isn't enough oxygenation, corys can have problems. Now I'm running powerheads in all the tanks that have catfish. They certainly won't hurt.

I have two filters with lots of water disturbance so shouldn't be an issue with oxygen. I use buckets for water changes and do 50-75% weekly changes. Hopefully daily changes for a week help.