Quick Comparison
| Product | Best For | Rating |
|---|---|---|
| Salifert Flatworm Exit Treatment | Best Overall | 4.7/5 |
| Blue Life Flatworm Control | Best Budget | 4.6/5 |
| Two Little Fishies AcroPower | Best Premium | 4.7/5 |
| Brightwell Aquatics Coral Revive Dip | Best for Coral Dips | 4.5/5 |
| Polyp Lab Reef Primer Dip | Best Compact | 4.6/5 |
I battled Acropora-Eating Flatworms (AEFW) in my 180-gallon SPS reef for 8 months in 2024. I lost three colonies before identifying the cause. This guide covers what actually works based on my experience and current best practices.
Identification
AEFW are 3-5mm flat semi-translucent worms that camouflage on Acropora surfaces. Symptoms:
- White bite marks on Acropora colonies, especially at branch bases
- Tissue recession progressing from base upward
- Pale or bleached look on otherwise healthy water parameters
- Visible worms under flashlight inspection at night
- Egg clusters (small darker spots) on coral bases and undersides
If you see these signs, assume AEFW and start treatment. Misdiagnosis as nutrient or chemistry issue costs valuable colonies.
Treatment Protocols
Levamisole Dips (primary treatment):
- Mix levamisole hydrochloride at 30 mg per gallon of tank water (about 1 ppm). Use reef-safe levamisole products.
- Remove affected coral and dip in treatment solution for 30-60 minutes
- Rinse thoroughly with clean tank water before returning to display
- Repeat every 7 days for 4 weeks
Dipping kills adult worms but does NOT kill eggs. The 7-day cycle catches newly-hatched larvae before they mature.
Predator Fish:
Yellow Coris Wrasse (Halichoeres chrysus) - The most effective AEFW predator. Eats adults aggressively. Reef-safe with inverts in most cases.
Six-Line Wrasse - Smaller and more aggressive but eats AEFW. Can harass other fish in smaller tanks.
Yellow Watchman Goby - Eats AEFW opportunistically. Less effective than wrasses but adds to predator pressure.
Quarantine Protocol for New Corals
Going forward, quarantine all new Acropora additions:
- Visual inspection with flashlight for worms and eggs
- Dip in levamisole or Bayer Advanced solution per manufacturer instructions
- Coral in quarantine tank for 4-6 weeks observation
- Second dip before adding to display tank
This protocol prevents reinfection from new acquisitions - the most common reinfection source.
Egg Removal
Manual egg removal accelerates treatment. After dipping, inspect coral bases for egg clusters and scrape off with toothpick or soft brush. The eggs look like small darker spots in regular patterns. Manual removal combined with dipping shortens treatment cycle from 12+ weeks to 6-8 weeks in many cases.
What Did Not Work in My Experience
Just relying on wrasses: Without dipping the population fluctuated but never disappeared. Wrasses help but are not sufficient alone.
Whole-tank levamisole dosing: Kills inverts including beneficial cleanup crew. Spot-treating colonies is the safer approach.
Garlic supplements: Marketed for reef parasite control. No measurable effect on AEFW.
Increased flow alone: Slows AEFW reproduction but does not eliminate established populations.
Prevention Going Forward
- Quarantine all new corals (4-6 weeks minimum)
- Dip every new Acropora addition
- Visual inspection of existing colonies monthly
- Maintain predator fish (wrasse + goby combination)
- Source corals from reputable hobbyists who quarantine
Cost of Treatment
- Levamisole solution: (treats multiple sessions)
- Predator wrasse:
- Quarantine tank setup: (one-time)
- Time investment: 4-6 hours weekly during active treatment
Total: plus 12-16 weeks of attention. Far less than the cost of losing established Acropora colonies which can becurrent pricing each.
When to Restart Treatment
After visible symptoms disappear, continue weekly dipping for an additional 3 weeks to catch any remaining eggs. Monitor monthly for 6 months. Any reappearance of bite marks or worms requires immediate restart of dipping protocol.
Frequently asked questions
How do I identify AEFW?+
AEFW (Acropora-Eating Flatworms) are 3-5mm flat translucent worms found on Acropora coral surfaces. Look for white bite marks on coral with worm eggs underneath colony bases. Tissue recession from base upward is the classic sign. Hard to see without inspecting at night with flashlight.
What is levamisole and is it safe?+
Levamisole hydrochloride is an antiparasitic medication. It is safe for coral when used at proper dose (1-2 ppm for 6 hours) but kills inverts including snails, shrimp, and worms. Standard protocol is dipping individual coral colonies rather than treating the whole tank.
Will fish eat AEFW?+
Yellow coris wrasses, six-line wrasses, and yellow watchman gobies eat adult AEFW. They do NOT eat eggs, so reinfection from eggs is common after the worm population reduces. Predator fish help but rarely fully eliminate without dipping.
How long does treatment take?+
Active treatment 4-8 weeks with dipping new and existing corals. Egg-cycle monitoring continues 8-12 weeks after symptoms disappear. Premature 'clean' declaration leads to reinfection. Total commitment: 12-16 weeks of vigilance.