The key is dry, controlled storage rather than simply sealing gear in a bag. A hard waterproof case such as a Pelican-style case can offer strong physical protection and helps isolate gear from humid air, but if moisture is trapped inside when you close it, the case alone will not prevent fungus.

For long-term storage, keep equipment in a clean, low-humidity environment and avoid sealing in existing moisture. Silica gel can help, but it should be used as part of a broader dry-storage approach, not as the only solution. If you use a sealed case, make sure the gear is dry before storing it and refresh or replace desiccant regularly.

Also consider whether your local environment is actually humid enough to create a significant fungus risk; that determines how aggressive your storage solution needs to be.