Puffer Massacer - dead bodies everywhere

[eatsomepopcorn]

Every morning when I wake up my saltwater fish they are all up at the top waiting for breakfast. On Christmas morning I woke them up and nobody came to breakfast - not a sole showed up. This never happended before. I looked around and spotted a dead damsel. I looked harder and in the castle a dead Domino Damselfish and my cute little Valentini Toby (Canthigaster Valentini). My lunar wrasse and clownfish were no where to be found. Needless to say I was devistated. I began bagging the dead bodies and moving rocks around and I uncovered my wrasse and clownfish that were still barely alive. I quickly set them up in a 5 gallon bucket and changed out 50% of the water, airstone and heater. I took 3 bags of water to the LFS and my bodies for answers. There were no answers, just speculation. Most of the fish are between 3 and 4 inches. The Amonia was 0, Nitrite 0, Nitrate 10-15PPM, PH was low (high 7x -I dont remember the exact number as I was upset). I do know that I had that PH checked one week prior and it read 8.1. The oxygen level was on the low side, but not low enough to kill the fish - again not 100% sure but around 7. The tank is 44 gallon with crushed coral, fluval 305 mechanical filter, 8 lbl live rock, aquipure denitrator (only 3 weeks old), however. Salinity was 1.022. The tank was running for 11 months. Last thing that I did was as follows. The night before I performed a 5 gallon water change. I took out the 5 gallons. Scraped off the brown algee that was covering a 5 sides of the pentagon with a powerhead running the whole time, but main filer off for cleaning. I had to run to the store for more charcoal so I actually left the fish sitting in this algee water which I could barely see through for approximately 3 hours before getting the filter going again. Powerhead was running but it was at the bottom of the tank. I added the 5 gallons of water and withing a few hours the tank cleared up 80% and at 11pm they were all up and seemed happy. At 9:30am the next day they were dead. The LFS theories include: (1) stirred up hypoxic pocket (bacteria pocket), (2) Low PH killed them (3) my theory (oxygen level killed them) (4) my new theory puffer released poison into the tank. The fish that died almost turned white - even the Domino - it was an erie site. So, what I did was tear the tank apart, clean it up well, remove crushed coral and put in 30 lbs of live argonite sand, added more live rock, added an airstone and whisper air pump and put my two surviving fish back in after 50 hours or so. The two survivors are doing great. I added a new Valentini puffer 4 days ago and he or she is doing great, getting along and eating well. What remains, however, is what killed my fish. I am guessing the answer is me, but I would like to know what I can do to prevent this going forward and if the steps that I took will help. I did purchase a master saltwater kit, which I did not have before. I had a strip test dry kit (dip in tank strip). I also purchased an oxygen test kit to keep an eye on oxygen level. I have a refractometer and I keep sg in check accurately. Prior to this my regular tank maintenance was 25% water change monthly. I bought the denitrator because I wanted to cut back on water changes and get rid of that brown alge. The denitrator takes 6-8 weeks to really kick in, however. One thing that I neglected to mention is that I kept the denitrator on during that 3 hour pump outage dripping one drop per second or slightly faster also. I am trying to come clean so that someone can tell me what I messed up here.

[crazedpuffer]

Sorry about your losses!

Chances are it's either
(1) stirred up hypoxic pocket (bacteria pocket) (2) Low PH killed them
But I don't think it's one. The low ph wouldn't do it but a PH swing would have.
A valentini would not release poison into the tank, they are only poisonous when digested, and can't release toxin into the tank (boxfish and cowfish can)
Also test strips are very innacurate stick with the new liquid test kit. Your tank was overstocked too. A lunare wrasse needs about a 90 gallon tank and becomes horribly aggressive. I wouldn't trust a denitrator to work, and your much better off doing the water changes.

Back on topic, It sounds like a PH spike killed off your fish. The same thing happened to one of my tanks about 2 years ago, it wasn't fun.
Was there any new LR added to the tank? It's possible an unwanted pest could have contributed.

[Nick]

Any chance you forgot to dechlorinate on that water change? It will whiten dead fish, and takes a few hours to do serious damage.

[bonnie3188]

IMO most fish will look very white when they are dead.

Possibility the Valentini bought in a disease? Did you QT him?

[eatsomepopcorn]

IMO most fish will look very white when they are dead.

Possibility the Valentini bought in a disease? Did you QT him?

The Valentini came in with the rest of the fish at the same time approximately 11 months ago - no new fish were introduced.

[eatsomepopcorn]

Any chance you forgot to dechlorinate on that water change? It will whiten dead fish, and takes a few hours to do serious damage.

No chance whatsoever. I always dechlorinate and it was only 5 gallons in a 44 gallon tank, but definately dechlorinated.

[eatsomepopcorn]

Sorry about your losses!

Chances are it's either
(1) stirred up hypoxic pocket (bacteria pocket) (2) Low PH killed them
But I don't think it's one. The low ph wouldn't do it but a PH swing would have.
A valentini would not release poison into the tank, they are only poisonous when digested, and can't release toxin into the tank (boxfish and cowfish can)
Also test strips are very innacurate stick with the new liquid test kit. Your tank was overstocked too. A lunare wrasse needs about a 90 gallon tank and becomes horribly aggressive. I wouldn't trust a denitrator to work, and your much better off doing the water changes.

Back on topic, It sounds like a PH spike killed off your fish. The same thing happened to one of my tanks about 2 years ago, it wasn't fun.
Was there any new LR added to the tank? It's possible an unwanted pest could have contributed.

I did not add anything to the tank that night - rock or otherwise. What could cause such a quick PH swing? My lunare wrasse is about 4 inches long and I purchased him at 3 inches. Prior to the death, he was picked on by a tank bully "Domino Damsel", now he thinks he is king of the tank swimming around, but does not harm or pester anything but the snail that lives under the sand. How do you really know when your tank is overstocked?

[beachbum]

Sorry about your losses!

Chances are it's either
(1) stirred up hypoxic pocket (bacteria pocket) (2) Low PH killed them
But I don't think it's one. The low ph wouldn't do it but a PH swing would have.
A valentini would not release poison into the tank, they are only poisonous when digested, and can't release toxin into the tank (boxfish and cowfish can)
Also test strips are very innacurate stick with the new liquid test kit. Your tank was overstocked too. A lunare wrasse needs about a 90 gallon tank and becomes horribly aggressive. I wouldn't trust a denitrator to work, and your much better off doing the water changes.

Back on topic, It sounds like a PH spike killed off your fish. The same thing happened to one of my tanks about 2 years ago, it wasn't fun.
Was there any new LR added to the tank? It's possible an unwanted pest could have contributed.

I did not add anything to the tank that night - rock or otherwise. What could cause such a quick PH swing? My lunare wrasse is about 4 inches long and I purchased him at 3 inches. Prior to the death, he was picked on by a tank bully "Domino Damsel", now he thinks he is king of the tank swimming around, but does not harm or pester anything but the snail that lives under the sand. How do you really know when your tank is overstocked?

How deep is your sandbed? This may be a stretch, but if there was hypoxic pocket (bacteria pocket) stirred up, your snail could have been the culprit.

[crazedpuffer]

If it was LS chances are a hypoxic pocket wasn't stirred up.
When was the last time you added LR to the tank?
Also a PH swing could be caused by a number of things, maybe bacteria and stuff from your hands had something to do with it. I know that's what went wrong with my tank when the same thing happened to me.

[t1gerbee]

maybe something to do with the 5 gallons you put in?

Was it pre-mixed salt or just RO?

If pre-mixed salt, what was the SG.. was it the same as yours? Was the PH the same as your tank? The temperature? Any of these could have caused a shaock change in.. (whichever was different)...

sounds horrendous, and has scared me quite alot. I'd be sorely tempted to jack it all in if that happened to me... but I hope you don't!

[t1gerbee]

just a thought...

maybe you had a power cut over night? significant drop in temperature....