infestation?

Question
I have a 55 gallon tank set up now for 10 years. I used to have ciclids but they killed each other off till there were just two large ones left. I traded them in for 2 severums. Those got very large and died last year. All along I have had silver dollars, and cat fish which have always done fine. So now I have 4 siver dollars, 2 catfish and a school of 11 neon tetras as well as 2 small algea eaters. All was fine till 4 weeks ago I noticed this strange almost feathery white strings forming a carpet over areas of the gravel and rocks. I have been siphoning this stuff out of my gravel along with water changes(50%) and filter cleaning(whisper 300. Ph is 7.8 . I have never seen anything like this and my silver dollars have been hiding in one side (no white stuff there) of the tank.

Answer
Hi Deb;

It could be a "plasmodial slime-mold" growth. They can take over large areas very quickly, as you obviously have discovered. (Yikes!) They actually feed on bacteria and the bacteria is feeding off of excess organic waste in the gravel. The solution really is what you are already doing. Keep vacuuming and cleaning. Cut back on feeding the fish too and it will help reduce the organic waste that the bacteria feeds on. Slime molds are not harmful to your fish but fish usually don't like it AT ALL. There must be something that comes from it that's offensive to them. Yuck.

Here is a web link to a forum with other hobbyists comments about what they have done to try to get rid of it;

http://www.aquariacentral.com/forums/showthread.php?t=7448

Pictures of some;

http://www.mikes-machine.mine.nu/specimens/Aquatic_slime-mold_Dscn8485.jpg

http://tc2tc.mojolingo.xuite.net/m2m-0000/waynesword.palomar.edu/slime1.htm

I really couldn't find anything else about it on the net to show you. You might want to do some research on your own to see if there is any more you can find out. Most of the slime-molds are terrestrial and can't live in your aquarium but they are all related. Hopefully yours will go away very soon. Pretty weird stuff.

At Your Service;
Chris Robbins