Panagrellus redivivus
species of worm
The free-living nematode Panagrellus redivivus (sour paste nematode, or beer mat nematode from its occurrence in constantly moist felt beer mats), is known to many aquarium enthusiasts and fish keepers as the microworm. It is a tiny roundworm used as the first food for larger kinds of newly-hatched fish, such as larval common carp. The microworm is widely used in aquaculture as food for a variety of fish and crustacean species.
One of thirteen currently recognized species of Panagrellus, P. redivivus is about 50 μm in diameter and just over 1 mm in length, barely visible to the naked eye. Subsisting on yeast, it is easily cultured at home on a substrate of flour paste or porridge inoculated with dry yeast. Females reach maturity in about three days and deliver live young rather than eggs, as most nematodes produce.
The microworm has been used in genetic analysis studies, but not nearly as universally as its relative, Caenorhabditis elegans.
In Vietnamese cuisine, it is common to use lactic-fermented yeast rice, or cơm mẻ, which contains the microworm (con mẻ) along with fermenting bacteria and yeast, to create a sour flavor in dishes.
References
Further reading
Kovaleva, E.S.; et al. (2003).
This brief starts where responsible research should: with the source description of “Panagrellus redivivus” as species of worm. Everything that follows is an evidence route, not borrowed authority.
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The subject matters to the science & nature register because the source frames it as species of worm. Its deeper value depends on whether names, dates, institutions and citations support that framing.
Datasets, specimens, observations and peer-reviewed methods provide the appropriate test for the technical claims summarized here. The source revision retrieved here is dated Aug 7, 2026. The linked authority identifier is Q7129875. None of the 0 selected statements returned an explicit reference. The first chronological checks are 2003.
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This entry incorporates text from “Panagrellus redivivus” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.