cobb webbs in my tank

Question
Hi I have a 30 gal tank and haven't had a problem until recently...yesterday I noticed my fish weren't eating and some where hiding and then I realized two were dead.  Upon closer inspection I noticed a Cobb-web like substance with white dots in it tangled all though out my floating plants....I have been fighting off snails recently but I don't know if the snails are whats suddenly making my fish sick...please help...I know most people just say they are fish but I am quite fond of my little swimmers...Thanks

Answer
Hi Marcy,
Snails do not cause disease or deaths in fish.  If a fish hides and then eventually dies, it is a sign of stress.  But there might be another cause to your fishes death.  The cobb-web like substance, is it light green and very thin?  There is an algae called thread algae and it can get extremely long, maybe even a few feet.  And its the only thing that resembles a cobb-web that I can think off.  It can be due to excess iron in the water.  Bring a sample water to your local fish store and have them test the water to see if anything is out of balance, causing the fishes death.  Another possible reason is nitrate build up if you never do water changes.  Be sure to do 15% water changes a week to keep nitrogen levels in check.
-Matt-