cichlidsickness said:Do you think they can be eradicated with frequent gravel vacs or only reduced in numbers?
I don't know if these can be completely eradicated. Some varieties are more resilient than others. In some cases gravel vacs with water changes are enough but not in other cases.
cichlidsickness said:So Naididae belong to the same family as Tubifex worms? Or are they in fact Tubifex worms?
Tubifex is in the Naididae family. Some aquarium worms don't look much like the picture below but I'd say yours resembles tubifex.

http://www.sanroque.net/srstudents/foss/popeco/organismdatabase/orgpages/1250.html