Fish all look sickly, yet water seems fine...HELP!

[naesco]

Originally Posted by asylumdown

Well, the first question should be what killed the tang? I'm sure a rotting fish in the water didn't help if it was a decently sized animal, but fish don't just die for no reason. Unless you've had this tank for years and years, chances are good it wasn't old age. If something stressed that guy out mortally there's a good chance others are being subjected to the same pressure.

What asylumdown said but:

Both a powder blue tang and an A.nigricans (looks like a powder brown tang but has no orange on it) will die for no apparent reason most often taking a few of their tankmates with them.