About 4:30am this morning the power went out. I never would have known(Except for blinking digital clocks) except wifey got up to go to the toilet and had to go in the dark. The power was only out for about an hour and a half, I checked both tanks, they were fine, all the fish seemed happy though a bit annoyed at me for shining a flashlight in their tank. So, I went back to bed happy that the fish were doing fine. About 10 wifey comes and gets me and I look in my 200L tank, there are corpses floating everywhere. Looks like I've lost all of my cardinals, I've found 7 and a few MIA. All of my rummy noses(6 found, 1 mia), both of my lampeyes, 1 lf zebra danio, 1 serpae, one black tetra(the only one) and 1 white cloud mountain minnow. All the other fish are looking pretty stressed and floating at the surface looking very unhappy. My Brazilian Puffer is looking pretty lethargic and one of the serpaes is swimming at an angle.
I'd just changed the water yesterday, and just finished another water change just now. Ammonia is 0, nitrates maybe 10ish, PH 6.9.
I've had the power out for longer than this without any problems before, but that's the only logical cause. That maybe this time the filter went anaerobic and dumped crap into the tank when it started up. But that doesn't make sense because the last few power outages were significantly longer and there didn't seem to be any trouble at all. Also, when I checked none of the fish seemed to be gasping for air or hanging around at the surface(Except for the ones that always hang around at the surface).
So, I'm sure you can guess that I'm not in a very good mood having lost half of a tank,(Not to mention $80ish worth of fish if no more die) apparently because the damn power company thinks that power cuts every other month are ok.