From The Aquarium Wiki
Black worms (often called California Blackworms®) or Lumbriculus variegatus are small worms that should only be fed when live and can be kept in the fridge to make them keep longer.
In cultured conditions grows up to 2.5-3.8cm (1-1.5") in length.
- All aquatic animals (fish, frogs, etc.) seem to like this food. It is very readily taken.
Black worms are available by mail order directly from Aquatic Foods, in USA aquarium stores, or from other USA fish keepers. It doesn't appear to be available outside the USA.
- Available as live food.
- Some aquarists wash this food with tap water using a fine tea strainer, coffee filter, or special "worm keeper".
- Rinse daily to keep the culture from going bad and harming your fish.
- Do not feed dead worms to your fish!
- Black worms are much more difficult to culture than most other forms of live food, however they can be cultured with some success in a 10 gallon aquarium. A substrate such as brown paper towels can be used for the worms to live in and eat once it starts to decay. Aeration is required, and water level should be kept to a few inches to maximize the amount of oxygen in the water, since worms will live on the bottom. It is often difficult to achieve the same amount of yields as other forms of live food, but they may reproduce asexually under these conditions. However, the possibility of keeping the worms with another live food such as also culturing daphnia int he same container makes the effort of culturing them much more bearable.
- Do not freeze.
- True black worms somewhat resemble tubifex worms but is generally healthier to feed to aquarium fish.
- Sometimes black worm cultures may have Hirudo sp. (leeches). These are most likely harmless to your fish and are just feeding on the black worms but you can remove them from your culture if they bother you.
- As with giving your animals any live food, there is the risk of adding parasites and dieases to your tank.