Mystery death of Coral Beauty AFTER qt.

[Madison Reef]

So I just lost my coral beauty which I had for about three years.
It was a model citizen. It never picked a fight or nipped at my corals, it was a center piece of my tank, and it lived up to its name "coral BEAUTY."

I used to not qt fish, so when I bought new fishes I decided to qt all fish I had in DT and let DT go fallow.

All I had in my DT were a clownfish and a coral beauty I had for about three years. No issues except one fish died when I moved my tank.

In QT, I added those two fishes from DT and bought one springeri damsel, two banggai cardinals, one yellow watchman goby (which was supposedly qt'ed from LFS. It died with white patches on his body), six line wrasse (which came with ich and what not, died).
Those two fishes mentioned above died in QT while copper treatment, others survived through the complete qt which included 30 days copper, 3 rounds of prazi, metro for 10 days.
I believe that yellow watchman goby had a issue with bacterial infection on skin. I'm not sure what happened with six line wrasse. Maybe too high copper level for it to handle.
I never had a good luck with a LFS I bought six line wrasse from. Not a single fish survived from that LFS, so I guess I might have asked myself for a problem when I bought six line wrasse.

Anyhow, 3days ago on Saturday night, I put remaining fishes (clownfish, coral beauty, two banggai cardinals, and springeri damsel) back to DT at night.
The next two days they were eating fine. No signs of stress or any problem.
Yesterday, I had a busy day so I did not have a chance to look at the tank.
Then, I saw my cleaner shrimp eating the dead body of coral beauty today morning, which is three days after putting them in DT.
I believe it died on Monday looking at its decomposed body.

What went wrong?
I do not think it was attacked by tank mates as they are all smaller peaceful fishes than coral beauty.
Possible disease after qt?
My water quality is fine considering acros doing just fine, though little pale from not having enough phosphate and nitrate.
Should I be worried for the rest fishes?

Please help.
Thanks

 

[blaxsun]

Did you complete the fallow cycle in your DT before returning the QT fish? QT can be very stressful/hard on fish period. I'm inclined to think there was either something in the DT (but if you ran it fallow, probably not) or the QT process was too much for your coral beauty.

 

[Madison Reef]

Did you complete the fallow cycle in your DT before returning the QT fish? QT can be very stressful/hard on fish period. I'm inclined to think there was either something in the DT (but if you ran it fallow, probably not) or the QT process was too much for your coral beauty.

I did complete 76 fallow cycle for my DT. Besides, there was no apparent issue going on in DT.
The reason for qt is not because there was on going issue in DT.

I thought copper treatment is considered to be harsh on fish, compared to prazi and metro being gentle.
What I do not understand is that coral beauty survived copper treatment and it was doing fine while being treated with prazi and metro after copper, but it died soon after it was being returned to DT.

Should I be worried with remaining fish in DT?

 

[blaxsun]

I did complete 76 fallow cycle for my DT. Besides, there was no apparent issue going on in DT.
The reason for qt is not because there was on going issue in DT.

I thought copper treatment is considered to be harsh on fish, compared to prazi and metro being gentle.
What I do not understand is that coral beauty survived copper treatment and it was doing fine while being treated with prazi and metro after copper, but it died soon after it was being returned to DT.

Should I be worried with remaining fish in DT?

I don't quarantine my fish. First and foremost, copper reduces their lifespan - even if they survive. Second, some strains of velvet (etc.) can slip through. Third, having no natural immunity to diseases and parasites tends to open one up to mass extinction events.

It could be due to the copper - or something else. All you can really do at this point is keep an eye on the remaining fish in your DT.

 

[Madison Reef]

I don't quarantine my fish. First and foremost, copper reduces their lifespan - even if they survive. Second, some strains of velvet (etc.) can slip through. Third, having no natural immunity to diseases and parasites tends to open one up to mass extinction events.

It could be due to the copper - or something else. All you can really do at this point is keep an eye on the remaining fish in your DT.

Thank you for your advice.

 

[blaxsun]

Thank you for your advice.

Having run your DT fallow and all the other fish through QT, it's reasonably safe to assume this was an isolated event. But best of luck going forward!