Why do fish die???

[labrown]

Today we lost our blue jawed trigger. But I have no idea why he died. We found him hidden under a rock, and he was very hard. When we moved the rock he floated to the top. There are no other fish in our tank, and all of our corals seem to be doing fine. So other than performing a fishy autopsy, we will never know why we lost him. We are checking our levels now, so far everything seems normal.
pH 8.0
Ammonia 0
Nitrite 0
Phosphate 0
Nitrate 0
I know our pH is a little low, but our lights just turned on. It will bump back up to 8.2 by the middle of the day. (yes, I know it is middle of the day already for some of you, but I work 2nd shift, so our lights don't come on until after noon)

So how can I find out what happened? He wasn't that big, so I didn't think he was very old. Maybe 3 inches long. He was pretty territorial so we didn't have any other fish with him. Now I am fishless... :(

[SABOB]

How long did you have him?Was he eating well?What is tank temperature?There could be many factors and possibly never know why.I hate losing fish but sometimes it happens when al parameters are correct.Sorry for your loss.

[g-ray]

Yeah sorry to hear it. Some times there is no way of finding out you can do everything right and it just works out that way :-(

[labrown]

Thanks for your reply. Tank temp is 80 and we have had him since July. He ate very well, we fed him cubes, pellets, and frozen krill. He ate just yesterday.

[ErikH]

Do you have a heater to keep the temp from swinging? Is your PH dropping lower than it should at night? I would guess some kind of temp related issue since it is now just getting cold. My tank dipped to 74 before I caught it, and I was glad I did!

[labrown]

Earlier this month our tank got cold overnight once, but our apartment is so small that we just keep it warm enough to keep the tank warm. Plus we have two little dogs that get cold easy, so we keep it nice in here. The pH fluctuates from 8.0 to 8.4, but we just put a light on our sump/fuge to try to counteract that at night. But last night we forgot to turn it on (too many timers, not enough room ). Hopefully I'll be getting a nicer timer for my birthday/christmas. Our tank usually stays between 78 and 80 on its own.

BTW it is a 55 gallon long with a 25 gallon sump, euroreef RS-80, liverock and crushed coral substrate, chaeto and live sand/rock in the sump/refugium.

Usually our cleanup crew goes strait for anything dead, but he was well hidden between two rocks. Our massive long spined urchin had no chance of getting in there to chow down.

Thanks everyone. Sometimes this is such a heartbreaking hobby...

[chark]

Sorry to hear about your loss. I also hate it when something in our aquarium dies.