Good foot hygiene is the first line. Wash all socks in hot water/bleach. Air out all shoes. Never wear damp socks, you may need to change socks during the day.
I have tried garlic cloves between each set of toes for as long as possible, normally sleep like that. However this may “burn” the skin. I have also read a daily foot bath in Calendula flowers infusion to be helpful.
Fugus likes dark moist places. Sunlight is always helpful.
It is important to find the root cause, which may be a sugar imbalance.