Så här stod det på en sajt:
When ammonia levels are high in the tank, a white slimy/moldy coating will grow on all surfaces of the tank.
If it is possible, remove the "stuff" from the tank. It would be a good idea to get your water quality tested. (ammonia NH3, nitrate NO3, and pH). I can help with any problems that might be occuring.
http://en.allexperts.com/q/Freshwater-Aquarium-3216/fungus-problem.htm
Kan det vara en ledtråd? Hög ammoniumnivå?