mysterious fish death

[fishy7]

I am watching a friends tank for 3 weeks while they are on vacation. The neighbor is feeding the tank while I just take care of filters and make sure the equipment is working correctly. I stop by ever 2-3 days. The feeding person has done this in the past but does not have the knowledge of SW. He is feeding algae sheets and 2 cubes. ( i know he is over feeding, I have had this conversation before)
270 Gallons
10 years old
Stock:
Naso 1ft long
coral beauty
1 yellow
1 purple
2 regals
1 pair false perks
Corals:
1 large colt
shrooms
frogspawn
WATER:
Trites 0
Trates 5
ammonia 0
Ph 8.2
Alk 9
Phos .03
Cal 420
SG 1.025
Temp 78
History:
3 days before the GFCI kicks off and the tank sits still for 8-10 hours. This is why I do not like them. It kicks for some reason and then you have issues if not caught in time.
Tank runs at 78 and drops to 74. Get the tank up and running all seem ok.
Next day all the fish are ok and swimming as usual. Back to normal.
Next day the Naso is swimming vertical in the rocks and does not look well.
Yesterday- he dies.

All the other fish have no issues. No parasites,ick or any other weird symptoms.

Any one have any thoughts on this. I told the owners and they were pretty upset as most would be.

The fish has been in the tank since 99 and is one of their best fish.
Thanks for any ideas.
:help:

 

[fishgeek01]

Not sure i would want to be the one to have to tell them something like that. Obviously it wasn't your fault though, i would venture to say that it has to do with the stress of the tank being off for that long. If the tang has been in the same environment for that long, and it suddenly gets changed like that i am sure it was very stressful. Not sure if it was stressful enough to kill it, but maybe so. The stress could have made an internal or other problem worse, thus causing him to die. Or perhaps it was just its time, and its an odd coincidence. Being that old and that large it could have been time.

 

[fishy7]

Thanks for your insight. It was not an easy call but one that is necessary. IT just plain su@k#$!
How long does a typical naso live?

 

[fishgeek01]

no clue on the life expactancy, but i imagine that it can't be more than 5-10 years. I know however that koi can live past 50 some even more. So maybe i am wrong on the 5-10 year thing.

 

[sebae*09]

you actually told them? i would have just went fish store to fish store looking for a big naso to replace it with lol.

 

[fishy7]

Thanks for the info!