Massive fish loss while on vacation

[krak256]

I left for a trip on Thursday and have been checking on my 150g tank via webcam everyday. My tank seemed fine up until Monday where my family members noted no fish have been swimming.

I contacted a local club member to swing by my home and they had to remove a bunch of dead fish: Achilles tang, purple tang, bi color blenny, starry blenny, 4 anthias, cherub angel, and a cleaner wrasse. A blue star leopard seems to be on its way out.

What does seem to still be alive are 2 clown fish, a leopard wrasse, and clown goby.

The club member said all my corals are as happy as can be, there wasn’t an electrical shortage, no anemone was stuck in the wave maker, the heater didn’t explode, the rest of the equipment seemed fine. I also checked my Apex and temp seems fine and didn’t see a warning or blip in electricity. A family member also confirmed they didn’t notice a power outage.

A 40% water change was done and new carbon was added. I did notice in video that my skimmer definitely increased since leaving, which may indicate it is pulling something out of the water.

The only things I did a few days before leaving was add some sps frags, remove a bunch of chaeto, change GFO, and top off rodi and two part.

What could have killed most of my fish?

 

[sc50964]

Got any pix of the bodies? Any signs of disease?

 

[krak256]

Got any pix of the bodies? Any signs of disease?

The club member said no signs of disease. All my fish were QTed and I haven’t added any new fish for a year.

 

[sc50964]

The club member said no signs of disease. All my fish were QTed and I haven’t added any new fish for a year.

Then it is likely some toxin that only affects fish but not corals…

 

[Townes_Van_Camp]

Toxins... or overfeeding by temporary care taker caused a bacterial bloom and hypoxia.

 

[sc50964]

Toxins... or overfeeding by temporary care taker caused a bacterial bloom and hypoxia.

Wouldn’t lack of oxygen affect water quality and corals?

 

[Ironwill723]

If you didn't QT the sps frags you could still have introduced a disease to the tank.

 

[Townes_Van_Camp]

Wouldn’t lack of oxygen affect water quality and corals

Not with certainty. I had a hypoxic tank about 10 years ago. None of the corals ever flinched.

 

[Lavey29]

We're you borderline overstocked? If so, one fish death could trigger a domino affect with ammonia poisoning.

 

[krak256]

Wouldn’t lack of oxygen affect water quality and corals?

Club member tested my water and said parameters were within normal range.

 

[SaltyT]

Sorry to hear about your losses.
Since your corals are unaffected the likely culprit is a disease perhaps brought in by the SPS frags.
The start of decomposition of all those dead fish is what probably increased your skimmer.

Are your remaining fish eating at all?

 

[krak256]

If you didn't QT the sps frags you could still have introduced a disease to the tank.

Sorry to hear about your losses.
Since your corals are unaffected the likely culprit is a disease perhaps brought in by the SPS frags.
The start of decomposition of all those dead fish is what probably increased your skimmer.

Are your remaining fish eating at all?

Other than velvet, what could kill fish so quickly? The club member said the fish did not show signs of velvet

 

[krak256]

Sorry to hear about your losses.
Since your corals are unaffected the likely culprit is a disease perhaps brought in by the SPS frags.
The start of decomposition of all those dead fish is what probably increased your skimmer.

Are your remaining fish eating at all?

I believe so. I had the auto feeder removed just in case there was something related to the food

 

[argiBK]

Something just like this happened to me a year ago. I’m sorry for your losses! I was on vacation and my housesitter fussed with the ATO, ended up drying out the return compartment in the sump and the fish suffocated from lack of oxygenated water. Corals, anemones were perfectly fine.

Could your return pump have cut out for a period of time and something similar happened? You mentioned it seemed like your skimmer was more active, water level rising in the sump from drain off could have resulted in this (depends on the skimmer type though).

 

[SaltyT]

Other than velvet, what could kill fish so quickly? The club member said the fish did not show signs of velvet

I believe so. I had the auto feeder removed just in case there was something related to the food

Typically the only symptoms of velvet are rapid breathing then death. Several fish dying in a short span of time makes velvet a suspect, but not necessarily the smoking gun. If your remaining fish are still eating and behaving normally then velvet is less likely to be the culprit. Are you able to see your fish in-person or are you still away watching on video?

 

[Lavey29]

Other than velvet, what could kill fish so quickly? The club member said the fish did not show signs of velvet

02 deprivation due to ammonia poisoning destroying fish gills

 

[Uncle99]

That was a big water change at 40%.

 

[Seansea]

Giessing house member put something in tank why you were gone. Decided to clean glass with windex tryimg to be helpful or something. Pit hands in tank with something foul on it. Prob why skimmer is actimg bad

 

[Sebastiancrab]

My bet is something toxic got added to the tank. Or you had a single fish die, and it set off an ammonia bloom which killed others. If it were a disease on a frag, other fish would come down with still.

I travel too and suggest you put Poly Filter in your tank before you go. It will catch a number of toxins. With your Wyze camera count your fish as part of your check. Have an automatic airstone and dual feeders set up (at different times). I also run with dual heaters each on their own Inkbird controller all the time. Upon traveling, I move one to the DT. I watch the water coming out of the return pump at the top of the tank and monitor the water level in the sump for the ATO.

 

[SaltyT]

Any toxin capable of wiping out almost every fish in the tank would also kill corals... all corals are fine according to the OP so a toxin isn't the cause.