Hi..I've tried both bloodworms and tubifex and they look like tubifex. The bloodworms look thicker and seem to get out of the feeder much easier. The tubifex 'clump' more and sorta cling to each otherand are thinner.....the fish have to tug more at the tubifex. BTW....I'm probably being paranoid, but, I don't think I"m going to get tubifex anymore. My lfs's keep telling me there is a higher risk of getting diseases from them. SH