Fish dying at night

[austenreefer]

Someone els

I had a 100% fish kill in a 10 year mature tank that was loaded with fish and coral. During a nighttime power outage for a few hours all fish were killed but no damage to coral.

No parasite or disease will kill in 12 hours. Lack of oxygen or ammonia will kill quickly.

Someone else suggested an ammonia spike too. Could be.

 

[Subsea]

Someone els

Someone else suggested an ammonia spike too. Could be.

While I respect @Paul B knowledge, if amonia killed fish, why did it wait for lights out. Oxygen is always lowest with lights out. Aggressive surface agitation is required in a reef tank at all times, however, it is critical when photosynthetic organisms consume oxygen and respire carbon dioxide which causes pH to drop. The pH drop is not the problem, but low oxygen is life threatening.

 

[austenreefer]

While I respect @Paul B knowledge, if amonia killed fish, why did it wait for lights out. Oxygen is always lowest with lights out. Aggressive surface agitation is required in a reef tank at all times, however, it is critical when photosynthetic organisms consume oxygen and respire carbon dioxide which causes pH to drop. The pH drop is not the problem, but low oxygen is life threatening.

My local fish store owner told me he thought it was oxygen related. I think that it’s most likely that, combined with the tanks maturity level.

 

[Paul B]

if amonia killed fish, why did it wait for lights out.

Thats just the time the ammonia levels got high enough to kill the fish.
Actually, I have no idea why they waited. Maybe they can't tell time. ;Woot

 

[MrDellimore]

Hey I was curious how your tank is doing now.
Did you ever add green chromis to the tank?

Did you find a solution to the oxygen issue?

I had a fish randomly die overnight with no sign of disease the night before as well

 

[OrionN]

If your tank does not have an overflow, or a skimmer, then the O2 at night is really low and this can kill fish and leave everything else not affected. This happen to me when I took the skimmer off line due to problem with the skimmer. I have to use a air stone until I get the skimmer fixed.