You should avoid consuming frozen fish if it displays clear signs of severe freezer burn, such as extensive dry white or grayish patches, deep dehydration, or if it has undergone multiple unauthorized thaw-and-refreeze cycles resulting in mushy texture, off-odors, or sour smells upon opening. Additionally, if the packaging is severely compromised, punctured, or if the fish has been stored in standard freezer conditions past its recommended shelf-life guidelines, discarding it is the safest choice to prevent foodborne illness.