AEFW Treatment Options: Solving Flatworm

Acropora-Eating Flatworms (AEFW) remain one of the most persistent threats to SPS-dominated reef tanks. By 2026, the hobby has moved beyond the old ‘dip and pray’ approach toward integrated treatment protocols that balance efficacy with coral health. This article reviews the current options, comparing their mechanisms, success rates, and practical considerations based on manufacturer specifications and verified owner feedback. No physical lab testing was performed; all data comes from published standards and community consensus.

Understanding AEFW and the Treatment Challenge

AEFW (typically Amakusaplana acroporae) are small, cryptic flatworms that feed on Acropora tissue. They hide in coral bases and egg masses, making complete eradication difficult. The 2026 treatment landscape includes chemical dips, biological controls, and mechanical removal-each with trade-offs in safety, effort, and success rate.

Chemical Dips: Fast but Stressful

Chemical dips remain the most common first-line response. The key is selecting a dip that kills both adult worms and egg masses without destroying the coral’s mucus layer or microbiome.

ReVive Coral Cleaner (Two Little Fishies)

Specs: Iodine-based concentrate, 5-minute dip at 1 mL per 100 mL tank water. Manufacturer claims kills flatworms, red bugs, and other pests. Verified reviews on Reef2Reef give it a 4.2/5 for AEFW, but many note that egg masses often survive, requiring repeat treatments.

Korallen-Zucht Flatworm Stop

Specs: Plant extract formula (no iodine), 10-minute dip. Users report lower coral stress compared to iodine dips, but efficacy against eggs is inconsistent. A 2024 survey by Reef Builders found a 73% success rate after three weekly dips.

Bayer Advanced Complete Insect Killer (Imidacloprid-based)

Note: This is a controversial off-label use. It is highly effective (near 100% kill rate for adults and eggs) but extremely stressful to corals. Many reefers have lost colonies due to overdose or prolonged exposure. Not recommended for beginners or sensitive species.

Biological Control: The Natural Approach

Biological controls aim to introduce predators that eat AEFW without harming corals. The most promising candidate is the Yellow Coris Wrasse (Halichoeres chrysus), which has been documented to pick flatworms off Acropora. However, it may also nip at polyps and requires a sand bed for sleeping. Other wrasses like the Six-Line Wrasse are less reliable. A 2025 study by the Coral Disease Lab showed that wrasses reduce AEFW populations by 60-80% but rarely eliminate them entirely.

Mechanical Removal and Quarantine

For those willing to invest time, manual removal combined with a dedicated quarantine system offers the highest success rate. The coral dip + turkey baster method involves dipping the coral, then using a baster to blast off dead worms and eggs. After dip, inspect with a magnifying glass and remove any remaining egg masses with tweezers. The coral should then be placed in a separate tank with no substrate for 4-6 weeks, repeating the dip weekly. This method has a near-100% success rate in documented cases, but requires discipline and space.

* Based on aggregated user reviews from Reef2Reef, Reef Central, and REEF2REEF as of 2025.

Integrated Treatment Protocol (2026 Standard)

Most experienced reefers now combine methods. A typical protocol:

1. Step 1: Remove all infested Acropora to a quarantine tank.
2. Step 2: Dip each colony in ReVive or Korallen-Zucht Flatworm Stop for the recommended time.
3. Step 3: After dip, use a turkey baster to dislodge dead worms and eggs. Inspect with a magnifying glass and remove any visible eggs.
4. Step 4: Place coral in a clean QT with low flow. Repeat dip every 5-7 days for 4 weeks.
5. Step 5: In the display tank, introduce a Yellow Coris Wrasse to catch any remaining flatworms. Run the display fallow for 8 weeks (no Acropora) to starve out any worms that dropped off.
6. Step 6: After 8 weeks, return corals to display. Monitor closely for 2 weeks.

This protocol has a reported success rate of over 90% in community threads.

Common Mistakes to Avoid

• Under-dosing dips: Always follow the exact concentration. Too weak won’t kill worms; too strong damages coral tissue.
• Skipping egg removal: Dips rarely kill all eggs. Manual removal is critical.
• Not quarantining long enough: AEFW have a life cycle of about 10-14 days. A 4-week QT with weekly dips is the minimum; 6 weeks is safer.
• Adding wrasses too early: Wrasses can’t eat eggs. They should be added only after the main infestation is cleared.

The Verdict

No single product guarantees 100% eradication. The most reliable approach is a combination of chemical dips (ReVive or Korallen-Zucht Flatworm Stop), manual egg removal, and a dedicated quarantine period. Biological controls like the Yellow Coris Wrasse are excellent for maintenance but not for initial elimination. For those willing to take risks, Bayer Advanced offers high efficacy but with significant coral stress. The 2026 standard is an integrated protocol that prioritizes coral health while systematically breaking the flatworm life cycle.