banda

I have noticed black dusty mold formed in my 10 gallon fresh water fish tank. It is visible on some sea shells and some stones that I have placed in the tank. I had some algae on the glass that I took care of by scrubbing. I have six tetras in it and I feed them the wafers (I am sure it is better known as something else) and freeze dried blood worms. The water quality is good, but the filter needs to be replaced (about a week or two over due). I am concerned that the mold my affect the fish. Any suggestions on how to take care of it (aside from giving it a good scrub) and how to keep the mold from forming? Thank you.

Gunnie

Without seeing a picture and knowing more about your tank, I would suspect the mold is not mold at all but a different type of algae. If it's dark brown, and not truly black, then it's probably diatoms, and will disappear within a few weeks. Diatoms are normal in a new tank. Here's a great article to help you determine if it's another type of algae you are dealing with:

http://plantgeek.net/article_viewer.php?id=9

Harley

if it is mold be sure that your fish do not eat it! also i would take out the decor that has the mold on it and clean it then do a vacum of your tank to rid the tank of mold change the filter and add new chemicals!!

banda

Thank you for the advice. I tried scrubbing when vacuuming and the spots seem to stay. I guess I should take the shells and the rocks out and give them a good scrubbing. Like in the link you've sent, the shells were initially brown due to algae. I thought the browning was the tetracycline that I used sometime back reacting with the calcium in the shells. Now the shells also have blackish spots which I thought was mold.