Lumbriculus variegatus – Blackworms
Author: Simon Check
First published in Aquarium World Aug 2011
Few fish can resist a wriggling worm as part of their diet. Blackworms are ideal live foods for your fish for the fact that the worms are easy to grow and will survive almost indefinatley in your tank until eaten, thus preventing pollution due to decomposition.
Although not bred or found often in New Zealand, Lumbriculus worms are actually quite common. They resemble Tubifex worms in appearance but this species of worms live in shallow water marshes, ponds, and swamps, feeding on microorganisms and organic material, unlike tubifex which prefer deeper less sanitary conditions. Reproduction is by division of the worms many (up to 150-200) segments, where each segment is able to develop into a fully functional individual. Sexual reproduction does occur, but is not very common. They can reach to approx 10cm in length when fully extended.
Lumbriculus uses its head to forage in sediments and debris, while its tail end, specialized for gas exchange, often projects upwards, When disturbed they will quickly contract itself into the sediment or swim away in a corkscrew fashion.
Photo: Simon Check
Breeding Blackworms
First task here is to acquire some blackworms. You can either ask other fish keepers if they can spare a few or you can search for some yourself. The most common way to find them is in the sediment or gravel in the bottom of Garden ponds. The image above is of an abundance of blackworms living in a Trout rearing pond ( the supply of food for the worms is in abundance due to the public feeding of trout at the viewing window). Most ponds and or streams/ditches have blackworms, you just need to find them. Favorite micro habitats include layers of decomposing leaves, submerged rotting logs, or sediments at the base of emergent vegetation
To breed these worms all you need is a small glass tank or container ( glass so you can view from the side), an air pump and air powered filter, Turkey baster/Syringe, some gravel and clean chlorine free water.
My setup is just a basic 20 X 20 X 20 cube tank, with a few cm of gravel. A cheap air powered sponge filter to keep the waste levels down is situated in the middle of the tank and the worms are simply introduced. There is conflicting information about as to the temperature that the tank should be kept at, but for best results I keep mine around 18 degrees Celsius. The worms will certainly survive much cooler temps but growth rates are dramatically reduced with the reduced temperatures. Simply add the gravel and half fill the tank with chlorine free water. Introduce the worms and add a small bit of decaying leaves and leave them for a day or two before feeding. This addition of the decaying leaves initially and after water changes in my experience has resulted in the reproduction rate initially increasing faster than without. I do not feed for the first day as I allow the worms to acclimatise to the changes and avoid polluting the tank.
Feeding is simple. I feed mine fish food ( a handy use for that cheap supermarket fish flake that the mother in law gave you for Christmas). I just sprinkle a pinch in every few days and do not feed again until I cannot see the flake on the bottom. The worms live in the gravel and they can be seen congregating around the fish food.
Maintenance is minimal and involves just water changes and if the culturing is going well they will eventually require a full clean out as they produce a fair amount of waste which will foul the water. Simply gravel vac the tank into a bucket and don’t worry about sucking up the worms. You retrieve them from the bucket once the contents of the syphoned bucket is settled using a turkey baster or large syringe. The worms will just bunch up into a ball and are easy picking. Rinse them with fresh water and feed out half of them and then replace the remaining half in the worm tank.
Collection of worms to feed out between tank cleanups is as simple as stirring the gravel up and using a turkey baster/syringe to suck the worms up as they wriggle about in the water. Most fish will snap these up before they can escape. Apisto’s and Corydora love them. My Geophagus love them. Haven’t had a fish that doesn’t yet.
Collected worms ready for feeding out.
Photo: Simon Check
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