Hi,
From your pic, that doesn't really look like fungus to me. Fungus usually presents itself as soft and cotton or wool like. Also that leg appears deformed, is it or is it just the pic?
If it is another form of growth, I would suggest fridging him and seeking a vet's advice.
As for the toes turning white, do you mean on that foot or are all his toe tips turning white on all his feet? If this is happening on the tips of all his toes, it could just be pigment change or a sign of maturity, depending on the axolotl's age.
I am concerned about the look of his gills, have they deteriorated or is this how they have always been?
Sorry, Fungus is treated with salt baths and if this is not fungus, you could end up stressing your axolotl more for no reason. A better pic and/or some more info would be very helpful, thank you.