Like tubifex worms, blood worms are enjoyed by most if not all fish. Unlike tubifex worms, they do not lump together at the bottom but wriggle in midwater.
The advantage of feeding bloodworms is that they are well liked by fish but does not carry disease like tubifex worms are thought to.
Blood worms are available in frozen cubes as well, which is a very convenient way of feeding them. Individual cubes can be pushed out from a slab that they come in. One thing to note is that you should quickly wash your hands after you handle them with your bare hands, as there are people who get an allergic reaction by skin contact with the worm proteins that leech from the worms through skin that got broken by the freezing.
Blood worms also come in freeze dried form. However, they are light and when introduced to the tank water, will spread thinly on the surface of the water. For some reason, fish does not like to eat freeze dried bloodworms. In fact, some fish even take some time to recognise them as food.