When defrosting the fish balls, thaw them in the refrigerator overnight or under cold running water for a quicker thaw. It's important to cook the fish balls thoroughly after thawing to an internal temperature of 165°F (74°C) to ensure food safety. If stored appropriately and defrosted safely, consuming fish balls that have been frozen for 1 month should generally be okay; however, it's always better to follow specific guidance or food safety regulations for frozen fish products or check with the product's manufacturer if you have any doubts about its quality or expiration date.