tubifex worm
noun
tu·bi·fex worm ˈtü-bə-ˌfeks- 
ˈtyü-
: any of a genus (Tubifex) of slender reddish tubificid worms that live in tubes in fresh or brackish water, are widely used as food for aquarium fish, and serve as a host for the protozoan causing whirling disease in fish
called also tubifex
Word History
Etymology
New Latin Tubific-, Tubifex, from Latin tubus tube + facere to make — more at do
First Known Use
1948, in the meaning defined above