fungus problem?

Question
i have a 50 gallon tank with a red devil jack dempsey jewel cichlid and a pleco i used to have a dojo loach but it died. i think it had a fungus and i tried to treat it with pills but it if it was that it was to late. Can this be given to my fish that are there now? I also have noticed this white fuzz forming around the bottom of my hanging filter and around the tank i am not sure what it is but could it be the fish food growing mold on it ? if so how can i prevent it?

Answer
It is possible to spread diasease between fish, although this is not likely. Dojo loaches are suceptable to a kind of bacterial infection. It starts as a small white patch, and grows exposing the flesh below. It can be treated with broad spectrum anti-biotics such as Maracyn, or Maracyn II It is usually fatal, and I have heard of no successful treatment. It is often tied to poor water quality. I wouldn't treat the other fish unless you see something on them as well. A 25% water change would be a good idea.

The white moldy substance could be excess food gone bad, or it could an animal carcass decomposing. It could also be a symptom of poor water quality. 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.

Good Luck.