Need Help With Fungus!

[-FighterFishh]

No, the medication wouldn't hurt. It's just bad practice to treat when you don't know what's wrong, and with what might be the wrong med. It helps parasites, viruses and bacteria evolve immunities to the meds if they're used inappropriately.

Okay ^u^
I've decided a course of action that doesn't use any medicine.
I'm going to do small water changes (2-5l) everyday, and also be adding small quantities of aquarium salt. I've been dosing aquarium salt anyway to help my guppy regrow his tail (he was being bullied, part of the reason I was changing the stocking in the first place) and I think this could be why the infection hasn't really gone very far, or spread to any other fish.
I'm also going to buy a biOrb first aid filter cartridge. Even though I'm skeptical about it, my mum seems to think that it couldn't hurt, and I agree. Hopefully this should sort out the white spot, and if not, I'll maybe look into some medicines, but not until I really do know what it is!