Blackworms Lumbriculus variegatus a second crop from trout

Blackworms (Lumbriculus variegatus), a second crop from trout farms by Louis Landesman, Ph. D

Cherokee Trout Farm, Cherokee, North Carolina

Rainbow trout, Cherokee Trout Farm

Blackworms Lumbriculus variegatus § Blackworms, Lumbriculus variegatus (Muller), are aquatic oligochaete worms living in ponds receiving effluent waters from fish farms. They are collected and sold as food for aquarium fish. Trout farmers in North Carolina and California collect blackworms from their effluent ponds. This activity provides a supplemental income for these fish farmers and helps recycle fish wastes which would otherwise pollute local streams.

Blackworm biology • The blackworm, Lumbriculus variegatus Muller, usually lives in ponds and lake shores containing abundant plant growth and decaying vegetation. As for fish food blackworms have several advantages. It is fully aquatic and will easily survive underwater until eaten by fish. For bottom feeding fish the blackworm is a food item that stimulates natural feeding behavior. Finally since it reproduces by fragmentation a constant supply of growing worms is easy to provide.

Blackworms in effluent pond

Blackworm production • Blackworms are harvested from the receiving ponds by hand. The water entering the receiving ponds is turned off allowing a worker to wade into the pond and collect surface mud containing these worms. The mud is then placed into long, shallow wooden troughs with fast flowing water running through them. Fine mesh screens are then placed over these troughs. The blackworms wiggle up through the screens in the presence of light. They are then collected and placed in separate running water troughs where the worms survive until needed by customers.

Blackworm troughs, Cherokee Trout Farm

Boxes for shipping blackworms

Beneficial Use of Effluents • The culture of blackworms represents a beneficial use of organic matter that would otherwise pollute surface waters receiving these wastes. The trout and sturgeon farms of California also raise worms on their effluent wastes. This activity sets a good example of how to treat aquaculture waste in a beneficial manner.