Panagrellus redivivus
Encyclopedia
The free-living nematode
Panagrellus redivivus (Sour paste nematode) is known to many aquarium enthusiasts and fishkeepers
as the microworm. It is a tiny roundworm used as the first food for minuscule newly-hatched fish, such as the popular pet fish betta
. The microworm is widely used in aquaculture
as food for a variety of fish and crustacean species.
The microworm is about 50 micrometers in diameter and just over 1 millimeter in length, barely visible to the naked eye. It is easily cultured at home on a substrate of flour
or porridge
.
The microworm has been used in genetic analysis
studies, but not nearly as universally as its relative, Caenorhabditis elegans
.
Culturing Temperature Should be: Room Temperature to 80 degrees Fahrenheit.
Life Span: Micro Worms generally live 20– 25 days and start reproducing at three days of age, bearing up to 40 live young a day.
Size: 1/16”
Medium Base/ Bedding: Oatmeal, cooked according to directions is recommended for best results. After it has cooked, add another additional portion of oats to thicken the medium into a paste. Place the oatmeal into a covered container and place it in the refrigerator overnight to cool and harden. By morning you should be able to cut the mixture into cubes and place them evenly to fit into the bottom of your culturing container.
Harvesting: Gather the worms that are crawling up the sides of your container with a stir stick or cotton swab and dip them into a small portion cup half filled with clean water. Gently stir to mix the worms and water. Using an eye dropper or pipette, feed the worms to your fry.
Sub-culturing: It's best to start a new culture every 2–3 weeks. Prepare your new medium and add a part of your old culture to the new one.
Notes of Advice: Because the worms are so tiny, a drop of these nematodes goes a long way. Do not overfeed small fry because the water will go bad very rapidly.
Your culture will eventually become watery. If it gets too watery, start a new culture.
If your culture starts to smell bad, immediately start a new one.
When using brewer's yeast to begin your culture, use it sparingly. If too much yeast is used, an overwhelming amount of carbon dioxide will be created which can suffocate your worms if there isn't enough air circulation within your culturing container, so make sure that you have punctured tiny holes in your culturing container.
Since these worms will climb the sides of the container, it's always best to place newspaper or paper towels on the bottom surface of their containers because these worms are known to escape through the air holes and onto the surface where they're being kept. This will protect your table or shelf.
Nematode
The nematodes or roundworms are the most diverse phylum of pseudocoelomates, and one of the most diverse of all animals. Nematode species are very difficult to distinguish; over 28,000 have been described, of which over 16,000 are parasitic. It has been estimated that the total number of nematode...
Panagrellus redivivus (Sour paste nematode) is known to many aquarium enthusiasts and fishkeepers
Fishkeeping
Fishkeeping is a popular hobby concerned with keeping fish in a home aquarium or garden pond. There is also a fishkeeping industry, as a branch of agriculture.-Types of fishkeeping systems:...
as the microworm. It is a tiny roundworm used as the first food for minuscule newly-hatched fish, such as the popular pet fish betta
Siamese fighting fish
The Siamese fighting fish , also known as the betta , is a popular species of freshwater aquarium fish. The name of the genus is derived from ikan bettah, taken from a local dialect of Malay...
. The microworm is widely used in aquaculture
Aquaculture
Aquaculture, also known as aquafarming, is the farming of aquatic organisms such as fish, crustaceans, molluscs and aquatic plants. Aquaculture involves cultivating freshwater and saltwater populations under controlled conditions, and can be contrasted with commercial fishing, which is the...
as food for a variety of fish and crustacean species.
The microworm is about 50 micrometers in diameter and just over 1 millimeter in length, barely visible to the naked eye. It is easily cultured at home on a substrate of flour
Flour
Flour is a powder which is made by grinding cereal grains, other seeds or roots . It is the main ingredient of bread, which is a staple food for many cultures, making the availability of adequate supplies of flour a major economic and political issue at various times throughout history...
or porridge
Porridge
Porridge is a dish made by boiling oats or other cereal meals in water, milk, or both. It is usually served hot in a bowl or dish...
.
The microworm has been used in genetic analysis
Genome
In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....
studies, but not nearly as universally as its relative, Caenorhabditis elegans
Caenorhabditis elegans
Caenorhabditis elegans is a free-living, transparent nematode , about 1 mm in length, which lives in temperate soil environments. Research into the molecular and developmental biology of C. elegans was begun in 1974 by Sydney Brenner and it has since been used extensively as a model...
.
Instructions for Culturing Microworms
Many fish keepers culture the microworm at home for their fry. There are many different ways to culture microworms. Some use a slice of white bread or oatmeal.Culturing Temperature Should be: Room Temperature to 80 degrees Fahrenheit.
Life Span: Micro Worms generally live 20– 25 days and start reproducing at three days of age, bearing up to 40 live young a day.
Size: 1/16”
Medium Base/ Bedding: Oatmeal, cooked according to directions is recommended for best results. After it has cooked, add another additional portion of oats to thicken the medium into a paste. Place the oatmeal into a covered container and place it in the refrigerator overnight to cool and harden. By morning you should be able to cut the mixture into cubes and place them evenly to fit into the bottom of your culturing container.
Harvesting: Gather the worms that are crawling up the sides of your container with a stir stick or cotton swab and dip them into a small portion cup half filled with clean water. Gently stir to mix the worms and water. Using an eye dropper or pipette, feed the worms to your fry.
Sub-culturing: It's best to start a new culture every 2–3 weeks. Prepare your new medium and add a part of your old culture to the new one.
Notes of Advice: Because the worms are so tiny, a drop of these nematodes goes a long way. Do not overfeed small fry because the water will go bad very rapidly.
Your culture will eventually become watery. If it gets too watery, start a new culture.
If your culture starts to smell bad, immediately start a new one.
When using brewer's yeast to begin your culture, use it sparingly. If too much yeast is used, an overwhelming amount of carbon dioxide will be created which can suffocate your worms if there isn't enough air circulation within your culturing container, so make sure that you have punctured tiny holes in your culturing container.
Since these worms will climb the sides of the container, it's always best to place newspaper or paper towels on the bottom surface of their containers because these worms are known to escape through the air holes and onto the surface where they're being kept. This will protect your table or shelf.
Further reading
- Schlechtriem, C., M. Ricci, U. Focken and K. Becker. (2004). The suitability of the free-living nematode Panagrellus redivivus as live food for first-feeding fish larvae. Journal of Applied IchthyologyJournal of Applied IchthyologyThe Journal of Applied Ichthyology is a scientific journal on ichthyology, marine biology and oceanography, the continuation of several differently-named journals on these subjects...
20(3): 161. - Kovaleva, E.S. et al. (2003). Panagrellus redivivus as a molecular model for cyst nematodes. Journal of Nematology 35(3): 348.
- Sautter J., Kaiser H., Focken U.,Becker K. (2007) "Panagrellus redivivus (Linné) as a live food organism in the early rearing of the catfish Synodontis petricola (Matthes)" Aquaculture Research, 2007, 38 (6) : 653-659