I have been out of the fish hobby a looong time.
My daughter's friend has a small hex tank that she just put two mollies in. She got them two days ago from Petco. The tanks previous occupant, a rainbow shark had died recently(put in a unclean bucket during a water change).
She just noticed today a cloudy layer on the bottom of the tank. It looks like cobwebs in layers almost. The water is slightly cloudy.
All I could think of is a bacteria bloom of some kind, and tomorrow I will hydroclean the gravel to get the guck out and do a partial water change.
Any thoughts from you fish people out there?