1 fish dead, 1 fish missing

[naesco]

Originally Posted by Coralgurl

Unless you find your missing fish the problem is likely a lack of oxygen event that caused some of your fish to die. Interesting... this may seem like a dumb question, but how would I check this? I have my returns pointed at the water surface and 4 powerheads, all working.
Alternatively, you can be experiencing a cycle. You should check your parameters. Will check when I get home.
Alternatively, you may have had a temperature spike. Possible - wouldn't this affect more fish? I unplugged my heaters before I left the house this morning simply because its supposed to be fairly warm today. My tank has been hovering around 81.5 over the summer.

It is doubtful that anything in your tank attacked, killed and ate two fish and killed and partially ate the other in one evening.Well it is Shark Week........

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On the oxygen and temperature and even ammonia issues different fish react differently. Some will die immediately others will hang in there enough to allow you to oxygenate the water or to correct the problem That is why some are still alive.

81.5 is not a problem at all but while you were out if it spiked to 84 or 85 it could be a cause of the problem. Opening the doors to the sump area and a cheap $29.00 pedestal fan will really help.

There are oxygen test kits but I have never used them.
All I know is that if you have mulitple fish deaths in one day it is often lack of oxygen, a serious ammonia spike, or overheating that is the likely problem.