All but one fish died within 4 hours

[papou667]

Hi, this is would be my first post but I have been on site for a good time now.

So last evening I did a good clean up of my tank and did a 30% wc. I went to sleep at 1am (6-7h after wc) and everything seemed fine, I woke up in the middle of the night at around 5 and all my fish were dead except for my ywg who is grasping for air. At first I taught my H. Magnifica who is now on the glass nuked the whole tank, but it doesn’t seem injured. I don’t know what to think honestly…

I have 3 blue leg hermit, 1 emerald crab, 3 snails and a tuxedo urchin that are all looking alive, not good but alive…

My nem still looks alive but not in good shape

My corals are not looking good either…

Candy cane
Zoas
Kenya tree
Galaxea

The tanks has been running for a little bit more than 6 months and everything was stable.

These have been my results for the last tests I did earlier this week :
Ammonia : 0
Nitrite : 0
Nitrate 10
Phosphate : 0.25
Calcium : 420
DKH : 10
Sal : 1.025

I started running carbon as soon as I saw the tank.

Any ideas what happened? I haven’t had any casualties yet except a few snails and a shrimp who was found split in half overnight a couple weeks ago

 

[tzabor10]

It sounds like the water change has something to do with it. Did you accidentally use the wrong water? It would help to test parameters now.

 

[twentyleagues]

I would also guess something with the water change. Ro/di? Tap? Did you match sg? Was the water a large diff in temp? Did you forget to turn anything back on after the water change? ( return pump/filter, power heads, Heater) How big is the tank?

 

[Gumbies R Us]

#fishmedics

 

[Sharkbait19]

Since inverts also died (and those corals are looking bad), you can rule out any fish diseases. The fish dying with open mouths indicates a potential low oxygen issue. How is your surface agitation? Was everything plugged back in?

 

[armyvetheather]

The way your fish are upside down it appears maybe ammonia? Are you using rodi water?

 

[Mr. Mojo Rising]

Is the water cloudy or its just the pic? Cloudy water could be a bacteria bloom, bacteria bloom depletes oxygen in the water, and you have a tall tank which is harder to oxygenate. I would guess that something you did caused a bacteria bloom and the oxygen level dropped too much.

 

[papou667]

Is the water cloudy or its just the pic? Cloudy water could be a bacteria bloom, bacteria bloom depletes oxygen in the water, and you have a tall tank which is harder to oxygenate. I would guess that something you did caused a bacteria bloom and the oxygen level dropped too much.

Looks like a bacterial bloom to me since it was crystal clear when I went to sleep, but I assumed it was the dead fish that caused it? But that would also make sense how they’re all dead with the mouth open like they were gasping for air…

 

[papou667]

It sounds like the water change has something to do with it. Did you accidentally use the wrong water? It would help to test parameters now.

I will def check my parameters today, but I expect them to be higher since I’ve just had a few dead fish in it for a few hours or am I wrong?

I would also guess something with the water change. Ro/di? Tap? Did you match sg? Was the water a large diff in temp? Did you forget to turn anything back on after the water change? ( return pump/filter, power heads, Heater) How big is the tank?

50gal + 8 gal refugium

I use distilled water since I live in an apartment and ro/di water is harder to find nearby.. SG was the same and temp was pretty close too +/- 2° colder, everything was plugged back in

 

[Uncle99]

Did you stir up the sand?
That can result in a temporary ammonia spike suffocating fish.

 

[papou667]

Since inverts also died (and those corals are looking bad), you can rule out any fish diseases. The fish dying with open mouths indicates a potential low oxygen issue. How is your surface agitation? Was everything plugged back in?

I have my return pump + the flow of my U4 at the surface making some movement, but I did drop a 2 power heads a little to try and make more flow on the sand bed, maybe this was detrimental?

 

[stE26wy14]

I have my return pump + the flow of my U4 at the surface making some movement, but I did drop a 2 power heads a little to try and make more flow on the sand bed, maybe this was detrimental?

a pic of water flow would help :D
sorry about your losses btw
maybe salinity change could've caused this, bacterial bloom can be caused by that
how r u feeding?
anything that u did in the past week would really help

 

[papou667]

Did you stir up the sand?
That can result in a temporary ammonia spike suffocating fish.

I did vacuum the sand bed while doing my wc since there was some buildup in some spots, could this be enough movement to cause a spike?

 

[Uncle99]

I did vacuum the sand bed while doing my wc since there was some buildup in some spots, could this be enough movement to cause a spike?

It can.
Sometimes pockets get released through cleaning.
If I vacumn I only do 25% max then nothing for a week.

 

[papou667]

a pic of water flow would help :D
sorry about your losses btw
maybe salinity change could've caused this, bacterial bloom can be caused by that
how r u feeding?
anything that u did in the past week would really help

I’m using an hydrometer which did give me a few problems a couple month back, but I cleaned it in vinegar and seems to be working properly rn… as for feeding a usually give pellets in the morning and a cube of mysis in the evening, I skipped the morning feeding yesterday since I was late for work… except that nothing different in the last week… I bought the candy canes 3 weeks ago and since it wasn’t opening I changed its location twice to try and accommodate him

 

[papou667]

Update : The zoas and Kenya are looking better atm, yet not as good as before and the ywg is still alive and doesn’t seem to be gasping for air as much as earlier…

 

[eliaslikesfish]

not sure if anyone mentioned it but the distilled water could have contributed to the issue.

 

[Dburr1014]

Bacterial bloom sucked up all the oxygen. Your fish suffocated.

Does the water ripple at the top?
How bad was the sand?
Only do a 1/4 sand bed stirring unless it is done often.

You stirred it up and a bacteria bloom started. Fish death is the end result.

Sorry for the losses.

 

[Sharkbait19]

It sounds like it was just a perfect storm of everything going wrong. Messing up the sandbed sounds like the major issue - between H2S pockets and trapped ammonia, a lot can go wrong. A bacterial bloom would starve the water of nutrients and O2 and you’re left with dying fish. The slightly reduced surface agitation probably didn’t help, but that alone wouldn’t have caused it.

 

[papou667]

It sounds like it was just a perfect storm of everything going wrong. Messing up the sandbed sounds like the major issue - between H2S pockets and trapped ammonia, a lot can go wrong. A bacterial bloom would starve the water of nutrients and O2 and you’re left with dying fish. The slightly reduced surface agitation probably didn’t help, but that alone wouldn’t have caused it.

That would make sense… I did dose seachem prime but I don’t think it would help with h2s, I ran carbon for a few hours after the wc also… any idea on what would cause the bloom? I was thinking a bloom after a vc would appear sooner after but it seems I was wrong:(