Feeder - Microworms (Panagrellus redivivus)

Microworms (Panagrellus redivivus) are another super-popular live food for fish fry—slightly larger than vinegar eels and very easy to culture, but a bit more “hands-on.”

Here’s how to keep a healthy microworm culture:

Basic Setup

Container:

• Shallow plastic tub with lid
• Poke a few small air holes (they need oxygen)

Medium (food + habitat):
Common options:

• Instant oatmeal (most popular)
• Mashed potatoes
• Baby cereal

Simple recipe:

• Mix oatmeal with hot water → thick paste (not runny)
• Let cool, then spread ~½–1 inch thick in container

Starter culture:

• Add a spoonful of microworms on top

Conditions

• Temperature: 65–80°F (18–27°C)
• Light: Not important (keep out of direct sun)
• Humidity: Lid keeps it moist

Maintenance

Microworms grow fast, but cultures don’t last forever.

• Add a tiny bit of fresh food every few days if drying out
• Start a new culture every 2–3 weeks (important—old ones crash)
• Keep 2–3 cultures running at different ages

Harvesting

After a few days, worms crawl up the container walls.

To collect:

• Wipe the sides with:
  • Finger
  • Cotton swab
  • Small brush
• Rinse into tank or feeding container

No straining needed like vinegar eels.

What they’re used for

• Slightly bigger than vinegar eels, but still tiny
• Great for fry that can’t yet eat Artemia
• Good for species like:
  • Bettas
  • Guppies
  • Tetras

Common Issues

• Smells bad: Culture is too old → restart
• Mold growth: Too wet or contaminated
• Drying out: Add a few drops of water
• Mites (tiny white specks moving fast): Start fresh ASAP

Key Differences vs. Vinegar Eels

• Microworms:
  • Grow faster
  • Easier to harvest
  • Need frequent restarting
• Vinegar eels:
  • Last much longer
  • Stay alive in water longer
  • Slower to produce
    

Pro Tip

Alternate feeding:

• Start fry on vinegar eels
• Transition to microworms
• Then move to Artemia nauplii as they grow