Multiple mysterious deaths overnight, help needed with causes

[Brian Berry]

Hello all,

A friend of mine has lost many of the fish in one of his tanks last night with no discernible reason as to what happened. He is looking for some possibilities as to the cause. Here is what I know so far.
He lost a Clown Tang, a Powder Blue Tang, a jawfish, a Copper banded butterfly, a fairy wrasse, 4 mandarins, a hawk fish, a cardinal and a peppermint shrimp. None showed any signs of illness. No spots or blemishes.
Two Clowns have been moved to another tank where they look sluggish.
A Blue Tang and a Foxface are still in the tank and showing no signs of stress at all along with a cleaner shrimp.
No corals show any sign of problems. It’s a mixed reef including some nps and a Colorado BTA.
This morning when he discovered the deaths Alk was 9, ph was 8.1, orp was 439 and temp was 77. Those are pretty stable numbers for this tank. An ICP test is being sent out.

He’s never experienced a loss of this magnitude with no explanation and is looking for possibilities to explore. I realize that there isn’t a lot ofinformation here to go on but if anyone has experienced something like this before where overnight everything went from being fine to massive fish loss in the morning, or has a suggestion on what might be a possible cause please feel free to jump in. Any thoughts or ideas are appreciated.

Here is a FTS from today after the dead fish were removed.
View attachment 2925641

Wow, I feel for him on the losses. Very nice tank. I hope people can give some input and figure out the cause.

 

[brandon429]

Biosecurity

A short introduction to aquarium biosecurity

www.reef2reef.com

There is the cause.

If we can see any post history for his tank I'll bet 99.9% we'd find wet items from a pet store vectoring in disease. Big tanks like that are always getting new additions, he'd need a strict Bs protocol to prevent these occasional fish kills

Find out when his last purchase from a pet store was

 

[Xenia]

Well if most of them died after feeding... I would be looking at that.
But a power out is possible, i notice a power out when my lights go on or of when its not the right time... And everything looks oke because i dont have a full stocked tank. ( Well got more fish now )

So perhaps with the fish dead the others had enough air then the power went back on and everything looked great again ( minus the dead fish) and then the owner gets home looks at his tank and notices only the dead fish.

 

[Jay Hemdal]

This is an older thread, but when I looked at it again, there is something I missed the first time - the ORP was reported to be 439. If the ORP probe is accurate, that is too high, and could have been a result of too many ozone oxidants in the water. If ozone wasn't being run on the tank, then the ORP probe is not accurate.

Jay