Short answer: It depends on your vow (pachchakkhān) and your tradition’s maryādā.

• If you are on complete fast (upvās or nirjal): No food at all, so no fruits.
• If you are on ekāsan/biyāsan/ayambil: Fruits are generally allowed, taken only in daylight, after careful inspection, and kept very simple.
• Shvetāmbara Paryushan (8 days): Many avoid green leafy vegetables; fruits are usually permitted unless your guru/gacch has instructed stricter rules (some families avoid fresh fruits on certain days).
• Digambara Das‑Lakshan (10 days): Many keep a plainer “boiled/simple food” discipline; in stricter observance, raw fruits may be set aside—follow your declared vow and local maryādā.

Simple guidelines if fruits are allowed for you:

• Daylight only; no eating after sunset.
• Wash, inspect well; avoid overripe/infested fruits.
• Prefer whole fruits eaten immediately; avoid processing, syrups, glazing, or cutting long in advance.
• When in doubt, choose the stricter option and follow your guru/sangh.

For easy Paryushan food rules and examples:

• What to eat during Paryushan
• Foods allowed during Paryushan (simple list)