Blackworm as fish food

 Blackworm made easy

Blackworms are known under various names, including California Blackworms, Lumbriculus variegatus, or simply Black Worms. Although the worms are not actually black. If you have an aquarium with ornamental fish and constantly need new live food, then the blackworm are a good choice. They are not only easy to breed, but also very popular with both large and small fish. After we dealt with the breeding of aphids in the last blog article on live food, this time it’s the worms’ turn.

Before we take a closer look at the breeding of blackworm, let’s take a look at the natural habitat. This is the only way we can breed Black Worms perfectly.

Natural habitat

The blackworms are native to Europe and North America and of course are found in aquariums all over the world. The natural environment is swamps, ponds and shallow waters. By the way, the blackworm is closely related to the earthworm, which we all know.

Nutrition of the blackworm

In nature, shiny worms feed on microorganisms and organic material. In your breeding you can use different food additives. It is important to note that some feeds produce more odour and cloudiness in the water than others.

Common food for shiny worms is:

  • Cider waste
  • Soybean flour
  • Spirulina powder (mix with water)
  • Fish food
  • Spinach
  • Oatmeal
  • Cucumber
  • Noodles
  • Salad
  • Foliage

If you feed with spirulina tablets or powder you will have the least water pollution and also no or little odour. Salads and leaves are more easily absorbed by the animals if you boil them with boiling water beforehand. You should always feed only as much as the animals eat, otherwise the leftovers will get rotten and the quality of the water will deteriorate again.

Advantages of blackworm breeding

Compared to other types of live food, the blackworm is a very easy to keep and high-quality feed. Pleasantly, it does not smell as strong as enchytrene and similar live food. On the contrary, it smells like nothing at all. If kept in a species-appropriate way it can be multiplied very quickly and is also very undemanding. It is important not only to choose the right equipment but also to keep the temperature. With great heat or too cold temperatures, natural reproduction is achieved. Here one saves a lot of money when buying live food or at least the way to the next dealer and the postage costs.

The nutritional value is probably unbeatable: The glow worms consist mainly of protein and have a low carbohydrate and fat content. So they can hardly harm your fish and do not cause fattyness of the fish. Compared to the Tubifex worm, the blackworm is the much better choice. Under the heading “breeding tanks” you will learn that only very little space is needed to create a breeding tank.

  • no smell
  • rapid multiplication
  • cheap food source
  • little space requirement
  • little work effort
  • very good nutritional value (compared to Tubifex)

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Breeding container

You don't need much to breed Black Worms. You can either put a bucket in the garden or on the balcony or put a small aquarium or bucket in the living room. Of course the aquarium looks nicer. Basically you can also use a bowl.

There are different ways of furnishing the aquarium. Either you lay out the floor with leaves and granules or you use artificial sponges. With natural sponges I had bad experiences with durability and also had problems to get the worms out of the sponge. Of course the granules and leaves are closer to the normal habitat of the animals but experience shows that the sponges are very well accepted.

The advantage of an external breeding container is that the worms remain as free of pollutants as heavy metals and parasites.

Temperature, water quality and ventilation

The ideal breeding temperature for optimal propagation is 15-26 ° C. You do not need a heating rod, the normal room temperature is sufficient. The tank needs a good ventilation. A sponge filter is recommended so that the blackworms are not sucked off. To keep the water quality constantly healthy, it should be changed regularly. I change the complete water every four days. Every 4 months I clean the pool completely.

Structure and reproduction

Adult blackworms are usually 5-6 cm long and consist of 150-260 body parts. You can see this in the video. Each ring is a body segment.

The worm has two possibilities to reproduce. One is sexual reproduction or reproduction by division, also called cross division. Similar to the earthworm, division is used to survive in predators. If a bird, fish or other predator bites off a piece of the worm, the rest of the worm can still survive. It regenerates itself and if you use this multiplication you can make two or three new worms from each worm.

I have read in other manuals that sexual reproduction only occurs naturally in the wild. I cannot confirm this. I only reproduce my black worms naturally without division. For this to happen, you simply have to imitate the natural conditions as closely as possible. A reproduction rate of 200% per month is normal. Professionals apparently manage up to 300%.

Storage as stock

If you do not want to breed the worms but store them, then it is recommended not to do this for longer than 2-9 weeks. The ideal storage temperature is 1-8 degrees, so perfect for the refrigerator.


There is a lot to observe when feeding, as the blackworm show an extreme hunting instinct even with full and calm fish. If you throw the worms into the aquarium as a thick ball, don't be surprised if the fish don't do anything at first. You will quickly observe how the ball of thread loosens and the worms leave the tank with comparatively high speed in all directions. From here the hunt begins.

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