Sudden Die Off?

[MonsterMinis]

My bet is on the silicone.. you seem to subconciousely point it out in your original post as your suspect.. and I agree.. it's entirely likely it didn't cure long enough.

personally I'de drain the tank and let it dry out for a week or 2. Give it a nice wipe down/rinse before re-filling it.

 

[aclockworkorange]

Wow, really? The silicone was one of my fears, and this seems to be the most likely scenario in my opinion. What did he do with the tank? Did he have to completely reseal, or was leaving it empty for a while after water contact enough for it to dry and be safe for fish again?

I'm actually not sure if he decided to re-seal. PM him. I know there aren't any fish in it right now (still)...