Symptoms to Look For
Check if your shrimp are showing any of these symptoms. Symptoms are grouped by severity to help you assess the situation.
Early Warning
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White or brown flat worms gliding on glass and surfaces
Visual: Smooth, flat worms 2-10mm long moving in gliding motion
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Worms with distinctive triangular or arrow-shaped head
Visual: Head clearly pointed/triangular with two visible eyespots
Moderate
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Shrimplets disappearing despite no other predators
Visual: Berried females hatch but babies vanish
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Worms congregating around food or dead organisms
Visual: Multiple planaria gathering at feeding spots
Severe
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Weak or molting shrimp being attacked
Visual: Planaria on or near struggling shrimp
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Population explosion of worms visible throughout tank
Visual: Dozens of planaria visible on glass, substrate, plants
Does this match what you see? If your shrimp are showing multiple severe symptoms, act immediately. Early symptoms give you more time to correct the issue.
Possible Causes
Causes are listed by likelihood. Start with the most common causes and work your way down.
Introduced on Plants or Decor
Planaria or their eggs hitchhike on aquarium plants, driftwood, and decor from other tanks. They're microscopic as juveniles and nearly impossible to spot.
Did you recently add new plants, wood, or decorations? Planaria often appear 2-4 weeks after new additions.
Overfeeding Creating Food Source
Excess food feeds planaria populations, allowing them to multiply rapidly. They're scavengers that thrive on uneaten food and organic matter.
Are you overfeeding? Is there uneaten food remaining hours after feeding? Reduce feeding and planaria populations often decline.
Introduced with New Shrimp or Livestock
Planaria can arrive in bags with new shrimp, on snail shells, or with any livestock from an infested tank.
Did planaria appear after adding new livestock? They may have been in the transport water.
Cross-Contamination from Tools
Using nets, siphons, or tools between tanks without sterilization can transfer planaria or eggs.
Do you share equipment between tanks? One infested tank can spread planaria to all connected tanks.
Present but Unnoticed Until Population Boom
Small planaria populations can exist unnoticed for months. An increase in food (overfeeding or death in tank) causes visible population explosion.
Planaria may have been present at low levels. A recent change (more food, dead fish) triggered visible numbers.
Solutions
Option 1: Chemical Treatment with Fenbendazole
Always do second treatment - eggs survive first dose
- 1
Remove all snails from the tank
Fenbendazole is lethal to snails. Move all snails to a separate container before treatment. This includes nerites, mystery snails, ramshorn, and bladder snails.
Any snails left in tank WILL die from treatment
- 2
Calculate dosage
Use 0.1 grams of fenbendazole per 10 gallons. No-Planaria packets are pre-measured. For Panacur C (dog dewormer), one 1-gram packet treats 100 gallons.
- 3
Dissolve medication and add to tank
Mix the powder in a cup of tank water until dissolved. Pour evenly around the tank. The water may become slightly cloudy - this is normal.
- 4
Wait 24-48 hours
Planaria will die within 24-48 hours. You'll see dead white worms throughout the tank. This is normal - they're dying.
- 5
Remove dead planaria and do water change
Siphon out dead planaria from substrate. Do a 25-30% water change. Dead planaria release ammonia as they decompose.
Monitor ammonia during this period
- 6
Repeat treatment after 3-5 days
Do a second dose to kill any planaria that hatched from eggs. Eggs are resistant to first treatment.
- 7
Final water change and snail return
After 1 week from last treatment, do 50% water change. Run carbon in filter for 24 hours, then snails can safely return.
Recommended Products
These are informational recommendations only. Not affiliated with any brands.
Option 2: Planaria Traps (For Minor Infestations)
Trapping alone rarely eliminates planaria - consider chemical treatment for complete removal
- 1
Create or purchase planaria trap
Commercial traps available, or DIY: small container with tiny holes, baited with raw meat (chicken, shrimp). Planaria enter but struggle to exit.
- 2
Bait trap at night
Place trap in tank at night when planaria are most active. Use raw meat as bait - they're attracted to protein.
- 3
Remove and dispose of trapped planaria
Remove trap in morning. Dispose of contents (don't pour down drain - freeze first). Never crush planaria as they regenerate from pieces.
- 4
Repeat nightly until no more caught
Continue trapping until you catch nothing for several nights. This reduces population but rarely eliminates completely.
Recommended Products
These are informational recommendations only. Not affiliated with any brands.
Option 3: Prevention Through Quarantine
- 1
Quarantine all new plants
Keep new plants in separate container for 2-4 weeks before adding to shrimp tank. Inspect regularly for planaria.
- 2
Treat plants with bleach dip (optional)
Quick dip in 1:20 bleach solution for 1-2 minutes kills planaria. Rinse thoroughly and dechlorinate before use.
Bleach can damage sensitive plants - not suitable for all species
- 3
Alum dip for plants
Safer alternative: soak plants in 1-2 tablespoons alum per gallon for 2-3 hours. Kills planaria without damaging most plants.
- 4
Never share equipment between tanks
Use dedicated nets, siphons, and tools for each tank. Or sterilize between uses.
- 5
Reduce feeding
Feed only what shrimp consume within 2 hours. Less excess food means less planaria food source.
Prevention Tips
Follow these practices to help prevent this problem from occurring in the future.
- Quarantine all new plants for 2-4 weeks before adding to shrimp tanks
- Treat new plants with alum dip (1-2 tbsp per gallon for 2-3 hours)
- Never overfeed - remove uneaten food after 2 hours
- Use dedicated equipment for each tank to prevent cross-contamination
- Inspect plants carefully before purchase - avoid tanks with visible planaria
- Avoid adding water from fish store bags to your tank
- Maintain clean substrate - vacuum regularly to remove organic debris
- Keep No-Planaria on hand for quick treatment if planaria appear
- Reduce protein-heavy feeding which encourages planaria growth
Related Parameters to Monitor
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Download FreePlanaria are flatworms in the class Turbellaria, and they're one of the few true predators that specifically threaten shrimp tanks. Unlike detritus worms (which are harmless), planaria actively hunt living prey. Identification is critical because treatment differs from other worms. Key features: - Flat, leaf-shaped body (not round like detritus worms) - Distinct triangular or arrow-shaped head - Two visible eyespots on the head - Gliding movement (not wiggling like other worms) - White, gray, brown, or black coloring - Size typically 2-10mm, can reach 20mm Planaria are dangerous because they: 1. Actively hunt and consume shrimplets 2. Attack weak, sick, or molting adult shrimp 3. Reproduce rapidly when food is available 4. Regenerate from body pieces if cut (don't crush them!) The hunting behavior is what makes planaria particularly problematic. They sense prey through chemoreception and will actively pursue shrimplets. A berried female can hatch 20+ babies, and planaria can consume most of them within days. Treatment with fenbendazole (the active ingredient in No-Planaria and Panacur C) is highly effective and generally shrimp-safe. The medication paralyzes the planaria, causing death within 24-48 hours. However, planaria eggs are resistant to treatment, which is why a second dose after 3-5 days is essential to kill newly hatched planaria. The main concern with fenbendazole treatment is snails - all snails must be removed as the medication is lethal to them. Shrimp typically tolerate treatment well, though you may see increased molting. Some keepers report occasional losses in sensitive Caridina species, so monitoring is important. After treatment, the dead planaria decompose and release ammonia. Water changes and vacuuming dead worms helps prevent ammonia spikes. Running activated carbon after treatment removes residual medication and allows snails to return safely.
Frequently Asked Questions
Healthy adult shrimp are generally safe from planaria. However, planaria will attack weakened, sick, or molting shrimp when they're vulnerable. The bigger threat is to shrimplets - planaria actively hunt and consume baby shrimp, which can prevent colony growth even if adults seem fine.
Yes, fenbendazole (No-Planaria, Panacur C) is generally safe for shrimp at proper doses. Most shrimp tolerate treatment well. However, remove all snails before treatment as fenbendazole is lethal to them. Some keepers report occasional sensitivity in Caridina species - monitor closely.
Planaria have a distinctive triangular/arrow-shaped head with visible eyespots and move in a smooth gliding motion. Detritus worms are round, thread-like, and wiggle frantically. Detritus worms are harmless; planaria are predators. If the head is pointed/triangular, it's planaria.
Planaria eggs are resistant to fenbendazole treatment. The first dose kills adult planaria, but eggs survive and hatch within days. The second treatment 3-5 days later kills the newly hatched planaria before they can reproduce. Skipping the second dose often results in reinfestation.
Traps can reduce planaria numbers but rarely eliminate them completely. Planaria reproduce faster than traps catch them in most cases. Traps are useful for minor infestations or in tanks where you can't use chemicals (sensitive species or with snails you can't remove). For complete eradication, chemical treatment is more reliable.
Most commonly from new plants - planaria or eggs hitchhike on aquarium plants. They can also arrive with new livestock, in transport water, on driftwood, or from shared equipment. They may exist at low levels for months until overfeeding or organic matter triggers a population boom.
Reducing feeding can decrease planaria populations by limiting their food source, but won't eliminate an established population. Planaria can survive long periods without food and will continue hunting shrimplets. Use reduced feeding alongside other treatment methods, not as the sole solution.
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Most shrimp problems stem from parameter issues. Track your water quality, get alerts when things drift, and prevent problems before they happen.