I've read that ketoconazole was effective as antifungal agent, to exhibit the fungi. But my plan is using it as the mixture of my nutrient agar to make sure only bacteria grows on it, not for determining nor killing the grown-already fungi on the media.

I've also heard about nystatin and cycloheximide that more common and also effective to be used as antifungi on nutrient agar, but for me they're a bit too expensive.