The free-living nematode Panagrellus silusioides is known to many aquarium enthusiasts and fishkeepers as the Walter Worms. They were first isolated and cultured when Helmut Walter isolated them in Germany in 2002. The Walter Worms are slightly smaller in comparison to the Microworms. They are 50 microns in diameter and 1.5 mm in length, barely visible to the naked eye. Walter Worms are irresistible to fish fry due to their constant restless movement underwater. They will survive submerged in water for approximately 24 hours. It is easily cultured at home on a substrate of flour or porridge. The Walter Worms are easy to see, you can see shimmering on the surface of the culture media.
Very little effort is required to culture Walter Worms. While accepting of a wide range of temperatures, the optimum yield will result from 20°C to 27°C. A Walter Worm female will start producing up to 60 babies a day after the fourth day. This will continue for the rest of their lifespan, which is 35 days.