The California Blackworm (Lumbriculus variegatus) is a valuable food for both freshwater and marine fish.  Fish that are reluctant to start feeding in captivity, from freshwater stingrays to marine butterfly fish can get their start in captivity using blackworms. As these worms are a “natural”food they approximate the nutrition in the diets in the wild.

To facilitate shipping by the worm farms to the purchaser, worms are treated to purge their systems of excrement and any undesirable organisms. This helps them arrive to you in viable condition. However, the process also decreases the nutritive value to your fish.