Not necessarily. There have been plenty of folks here that have had issues with contaminated frozen blood worms. I am not sure about tubifex, but they generally grow in dirty conditions and the freezing process won't necessarily decontaminate them. Someone might chime in here to confirm or refute my input, or give some direction. There are are reputable frozen blood worms but I do not use them so I cannot tell you what brand. Kenny Cheung uses frozen BW's in to feed his imports