What is this web like thing in my aquarium?

[asylumdown]

Originally Posted by FishinGoalie

What are your nitrates? looks like something a parrot fish would produce when sleeping.

+1. Do you have any wrasses? The kinds that don't bury themselves in the sand at night will often form a mucous bubble around themselves when they sleep that can look quite like that when it gets in to the water column and blows around. If it's not being produced by a fish or a coral, it's likely bacteria.