A string of random fish deaths with no warning signs spanning a couple of months

[Mark]

I've recently been experiencing fish losses. The fish will be fine one day eating and begging for food, and dead the next day. The last time I added fish was 3-4 months ago to get my nitrates up(they kept bottoming out). At that time I added 3 Azure damsels and 6 pajama cardinals. Slowly I would lose one fish at a time. No loss of appetite, no discoloration or spots.... I would find them dead, but in perfect condition. Almost as if they were killed instantly. No fin damage. I would lose one at a time. Once those Azure damsels and Cardinals died off, I decided not to add more fish for a while. I was down to a handful of fish I've owned for many years. Then this week my yellow tang of several years died the same way.

The tank is a reef xxl 625L. Temps are around 78 degrees. nitrates are zero. I run a UV 24/7.

I'm suspecting an internal parasite, bacterial perhaps. I debated whether it was a predator, like a mantis. My rock is gulf rock. I did remove a Mantis a few years back before he could do harm. I haven't heard any clicking, and I would think a mantis would inflict damage on the fish that I would see post-mortem. I also wondered about my Malu anemone, but it is heavily guarded by two 16 year old clownfish. And the anemone is only 4" wide.

I checked for stray voltage, and found none. I'm at a loss.

Right now, I'm beginning to feed with medicated foods. Some have antibiotics, and some have prazi for flukes/worms. Any ideas or is there something I'm overlooking?

 

[Phycodurus]

sincere condolences on the loss of your fish. ;Sorry

i was initially suspecting a mantis shrimp as i read your post but you are finding the dead fish “in perfect condition.”

stray voltage was my next suspicion but you’ve addressed that also.

i wouldn’t suspect the clownfish as going ultra-defensive of their anemone because your dead fish aren’t showing any damage.

a bacterial / viral outbreak of some kind is the next likely candidate imo.

what’s your alkalinity?
fish are pulled out before ammonia can spike?
any macroalgae in the tank?

 

[Jay Hemdal]

What fish remain in the tank? Fish loss with no symptoms is a tough one. When ALL the fish die at once with "no symptoms" we can pretty much guess that the symptoms were there, just missed by the aquarist. In your case, you observed the fish before and after death, and saw no clues.

Bacterial/viral issues are the "go to" in these cases because they often have indistinct or no real symptoms, and can cause chronic loss (versus acute loss, like seen with velvet or ich).

Jay

 

[hikermike]

Don't forget toxins like a cigaret from a party, a kid dropping something in and fishing it out or playing in the tank. Over treated water supply. Something surprising them? Is the tank old enough to have a hidden predator? Do you have a toxic coral you disturbed or a calupera? I've had the same thang happen, (we all have) and sometimes all you can do is tear it down boil and start over. (Don't boil a coral to kill it if it;s a Paly.

 

[Mark]

Thanks everyone, some good thoughts.

What fish remain in the tank? Fish loss with no symptoms is a tough one. When ALL the fish die at once with "no symptoms" we can pretty much guess that the symptoms were there, just missed by the aquarist. In your case, you observed the fish before and after death, and saw no clues.

Bacterial/viral issues are the "go to" in these cases because they often have indistinct or no real symptoms, and can cause chronic loss (versus acute loss, like seen with velvet or ich).

Jay

Currently all that are left are:

percula/darwin clownfish pair that are older then my kids(will be devasted to lose them)
a Kole tang
Randall's shrimp goby(no shrimp)
And a pair of Latezonatus clowns that live in my sump refugium

what’s your alkalinity?
fish are pulled out before ammonia can spike?
any macroalgae in the tank?

Alk fluctuates around 8-9 dkh. I dose 2-part with a doser staggered all day. The fish are pulled pretty quickly before decay. Interestingly, the dead fish float and end up attached to overflow or pumps. I do keep Caulerpa in the refugium, but I always have(23 years). I keep it harvested and avoid it going sexual.

Don't forget toxins like a cigaret from a party, a kid dropping something in and fishing it out or playing in the tank. Over treated water supply. Something surprising them? Is the tank old enough to have a hidden predator? Do you have a toxic coral you disturbed or a calupera? I've had the same thang happen, (we all have) and sometimes all you can do is tear it down boil and start over. (Don't boil a coral to kill it if it;s a Paly.

No parties. I do have kids but they know better than to mess with the tank. The tank is also in the basement, and kids are rarely down there. I have wondered about the water though. We've had a lot of neighbors complaining about water supply here this summer. Apparently, the large Lake water is sourced from has had some issues, and they are increasing chlorination occasionally. As a fishkeeper, I assume this means chloramines, but my RO/DI has a Chloraguard Block. And, the top off unit is pretty sensitive and only tops off a small amount at a time. And given my coral bioload, I would think any residual ammonia would be processed quickly. I haven't heard complaints from other local reefkeepers.

 

[Mark]

Here's a recent update about the water quality complaints I mentioned me and the neighbors are seeing:

Forsyth County Georgia > News

Forsyth County is conveniently located between Atlanta and the north Georgia mountains. The county is consistently ranked as one of the fastest growing counties in the United States. Forsyth County is a great place to call home and to do business. We have tax rates among the lowest in the metro...

www.forsythco.com

 

[Jay Hemdal]

Interesting that the dead fish floated, despite being pulled promptly. I’ve seen way more than my fair share of dead fish, and they just don’t float post-mortem until enough time has passed to produce internal decomposition gas....except in cases of supersaturation. Your sump probably never is allowed to run low because you have the latezonatus down there. Any chance of a leaking pump intake?
Jay

 

[Mark]

Hi Jay, can you explain the leaking pump intake? The refugium section is high, but the skimmer and return pump section are much lower in water height.

 

[Jay Hemdal]

Any time a pump sucks air on the suction side, there is a risk of gas supersaturation downstream. In severe cases all the fish just die. However, chronic cases can cause gradual fish loss, and then, if it is intermittent due to a sump sucking air for example, it can be really confusing to track down. However, there should be some other symptoms: thin air bubbles in the gills or fins, sometimes popeye. I doubt that this is the reason, just trying to rule stuff out....
Jay

 

[Mark]

Thx, that's interesting, I was unaware of that being an issue.