"Cobwebs" seen on fish, now everything dead??

[thincat]

Thats my guess man. If its the windows and door stuff it should be safe, but people say the II has to cure for like 3 days so it wont release ammonia and other nasties. The I is safer much earlier.

I'm curious why it wouldnt show in your testing, but its my main suspect at this point. Secondary would still be something completely random that your stirred up on accident or got into your tank.

I found this link:Aquarium Silicone 10.1 oz Tube Clear
It's made for Aquariums...