Can perforations or fistulas occur in the upper/lower gi without any symptoms or signs, after swallowing fish bone? worried i'll drop dead w/o warning

No: Dropping dead without warning is quite rare in modern life, with or without a fishbone. Our gut has a remarkable ability to handle small sharp objects, coating them and pooping them out. The things that cause perforations are objects like button batteries (electrochemical damage to our gut) and magnets (sticking together to cause pressure damage). The damage leads to pain and other symptoms.