though a fungus is usually a self surviving organism. Is this what you meant by true fungus francois? As in the difference between the common columnaris and a truly self propagating fungus
I suspect you're getting 3 different kinds of organism confused here.
Virus - Basically an envelope of protein with some genetic material inside. They're very small, representatives infect nearly every kind of living thing, including bacteria (these are calle bacteriophages) and they're not technically alive. They cannot replicate themselves and require the "machinery" of another living cell to replicate. What kind of cell they can invade and hijack is usually quite specific. So for example, an axolotl virus won't infect the cells of your java moss and vice versa.
Bacteria - Single celled organisms that can live in small clumps or chains. They can reproduce on their own via fission or splitting, producing two identical individuals. These organisms are classified as prokaryotic, that is, they don't have a nucleus. They do have genetic material but it's not organised into chromosomes like a human's is. You'll often hear them classified as "Gram negative" or "Gram positive", this has to do with the way their cell walls stain in a Gram's stain. The differences in the cell walls of different bacteria are often the reason why certain antibiotics don't work on certain bacteria.
Fungus - These organisms can reproduce on their own and include single celled organisms such as brewers yeast or multicellular organisms like mushrooms. Their cell walls are composed of chitin (the same substance that makes insect exoskeletons hard) and they are eukaryotic, they have a nucleus and chromosomes. Humans and Axolotls are both Eukaryotic but we don't have cell walls only cell membranes.
The differences between a prokaryotic and eukaryotic organism are vast and this combined with the way their cell walls are constructed means that antibiotics for a bacteria, quite often, don't work on a fungus. In fact penicllin is produced by a mold as a defence against invading bacteria.
I think Francois is trying to say that, without a microscope or some metabolic tests, it can be very hard to tell the difference between a fungal colony and a bacterial colony using the naked eye. Columnaris, a bacteria, apears as white fluffy colonies, apparently, as does a fungal infection. Treatment will work best if you are targeting the right kind of organism.
Hope this clears things up and hope it doesn't come across as condescending. If you have any other questions, please ask.
Back to washing my new sand substrate... *sigh*
-D-
