Can anyone tell me what this is kn my Mollie

[Summershine]

One of my monies has a patch on it's left side which looks a bit like white fluff. I have uploaded pictures, does anyone know what it is?

Thank you

 

[Byron]

It looks like fungus. This can appear on open wounds (if the fish may have scraped itself, or been bitten, for example). But with mollies there is also the possibility that it is from the water parameters if these are too soft (lacking in essential hard minerals) or the pH is acidic. Knowing your source water GH and pH should clear this up.