Fier is considerably safe at night. However, it's always a good idea to stay alert and cautious. While crime rates are relatively low, the city does have areas that are quiet and dimly lit, which might not be ideal for solo traveling at night. While you're unlikely to face any severe issues, it is prudent to avoid less crowded places and stick to well-lit, busier locations. Always remember no matter where you are globally, it is better to be safe and cautious, particularly when traveling alone.