Help! Lost half my fish overnight.

[ButteMTDIY]

Hello. Pretty upset with myself at the moment. Mistakenly left my sump return pump off overnight and tank dipped about 4 degrees. I have a second heater in display tank but apparently it couldn't keep up. Turned pump back on first thing in the morning and came home to some dead fish. Is a 4 degree temp swing in 24 hours enough to cause this? All my other parameters seem fine and so far the remaining fish, inverts, and corals seem ok. In a bit of a panic that im going to find the rest dead in the morning but unsure of what else i can do but assume it was a temp issue.

 

[JGT]

Hello. Pretty upset with myself at the moment. Mistakenly left my sump return pump off overnight and tank dipped about 4 degrees. I have a second heater in display tank but apparently it couldn't keep up. Turned pump back on first thing in the morning and came home to some dead fish. Is a 4 degree temp swing in 24 hours enough to cause this? All my other parameters seem fine and so far the remaining fish, inverts, and corals seem ok. In a bit of a panic that im going to find the rest dead in the morning but unsure of what else i can do but assume it was a temp issue.

Assuming your temp was around 78 so a drop to 74 shouldn’t have that much of an impact on the fish. It would have happened gradually as well. I would look for other reasons.

 

[ButteMTDIY]

Thats kinda what i thought too.

Assuming your temp was around 78 so a drop to 74 shouldn’t have that much of an impact on the fish. It would have happened gradually as well. I would look for other reasons.

Kinda what I thought too but at a loss as too what else could have caused. Getting ready to do a water change for lack of any other options.

 

[ShepherdReefer]

Maintaining a stable temperature is of the utmost importance, since the incorrect temperature or temperature fluctuations can cause stress to the inhabitants of the aquarium, and can lead to disease and algae outbreaks, or even death. This happed to me over 10-years ago when we lost our HVAC unit in the middle of summer and the temperature in the home was almost 90-degrees F. We lost many that day. Sorry for your loss.

 

[ButteMTDIY]

Maintaining a stable temperature is of the utmost importance, since the incorrect temperature or temperature fluctuations can cause stress to the inhabitants of the aquarium, and can lead to disease and algae outbreaks, or even death. This happed to me over 10-years ago when we lost our HVAC unit in the middle of summer and the temperature in the home was almost 90-degrees F. We lost many that day. Sorry for your loss.

Thanks Sheppard. Pretty busted up about it. I'm really attached to my fish and feeling awful guilty right now.

 

[BigRed78]

Maybe low oxygen? I know people that keep reefs at 74 degrees

 

[ButteMTDIY]

Maybe low oxygen? I know people that keep reefs at 74 degrees

I have pretty good surface agitation in display so i don't think it's that.

 

[mort]

My first thought would be the same as bigred78 and it's an oxygen issue. A temp swing even much larger than you have seen wouldn't kill fish but a large fish population and not enough oxygen would.

Apart from that it's hard to guess without knowing alot more about your tank, the fish you have etc.

 

[BigRed78]

I really don’t think it’s the temp I may be wrong but over the summer I lost power for a week and my tank stayed around 70-72 I only had slight bleaching on two sps corals that came back

 

[40g Nano]

What is your surface agitation?
A swing of only 4 degrees shouldnt do much if anything. imo

 

[BigRed78]

Also were any of the survivors swimming near the top or gasping when you saw your tank? If not oxygen I would guess it’s something unrelated to that temp swing.

 

[sfin52]

I had a heater go down middle of winter temp dropped to 70. I didnt loose a thing. I doubt 4 degree drop was the cause

 

[michaelmessinaglass]

Ive had my heater shut off in my last nano setup more than a few times, and Id wake up to a 68 degree tank. My ywg and pistol shrimp survived this 10 degree swing multiple times... corals survived too but looked super unhappy until the temp was 78 again. I don’t personally feel like 4 degrees would have done it. Ive broken down that flawed setup and had consistent temperatures ever since