Acropora Eating Flatworms (AEFW).

What AEFW are

Amakusaplana acroporae is a small (2-3mm) oval flatworm that feeds exclusively on Acropora coral tissue. They lay eggs in clusters on the coral skeleton between branches; eggs hatch in 5-9 days. A single hidden flatworm on a new frag can establish an outbreak that strips an established reef of all Acropora within 60-90 days.

Identification

AEFW are nearly transparent and notoriously hard to spot on the coral. Look for:

• Bite marks: bare white skeletal patches, usually at the base of branches and between corallites - classic "rasped" appearance
• Colonies pale or recede: the coral may stay alive but loses color and tissue progressively
• Eggs: small dark clusters on bare skeleton, distinctive from coralline algae
• Adult worms: visible only when dislodged from coral; rinse a frag in a small bowl of tank water and look at the bottom for tiny oval shapes that contract when disturbed

The dipping protocol (every new SPS frag)

1. Set up a small dip container with display tank water (1-2 cups depending on frag size)
2. Add CoralRx, Bayer Advanced Insecticide, or comparable iodine-based dip per label dose
3. Place frag in dip; agitate gently with a turkey baster for 5-15 minutes
4. Watch the bottom of the dip container - flatworms detach and accumulate visibly
5. Rinse frag in clean tank water (fresh container, no dip) for 30 seconds
6. Inspect for any remaining worms or visible eggs - manually scrape eggs off with a toothbrush or razor
7. Discard dip water (do not return to display)
8. Mount frag in display

Established AEFW infection (eradication)

Once AEFW are in a display tank with established Acropora, eradication is brutal. Options:

1. Frag everything and tank-transfer: remove all Acropora, dip and quarantine in a clean frag tank for 6-8 weeks while AEFW starve in the now-empty display. Most thorough but most disruptive.
2. Predator approach: some keepers use Yellow Coris Wrasse, Six-Line Wrasse, or Halichoeres species which prey on flatworms. Variable success - some wrasses don't eat AEFW.
3. Repeated whole-tank dosing: Salifert Flatworm Exit and similar products work on planaria but are unreliable for AEFW. Risk of toxin release if mass die-off.
4. Persistent dip + manual removal: remove every Acropora colony every 7-10 days, dip, return. Repeat for 6+ weeks. Labor-intensive but effective.

Prevention is the answer

Once an Acropora collection is large, an AEFW outbreak is catastrophic. The single best prevention is:

• Dip every new SPS frag, no exceptions
• Quarantine new frags in a dedicated frag tank for 14 days minimum
• Buy from reputable Fast Aquatics vendors with documented dipping protocols (Trust Score with packing certification confirms this)
• Avoid frag swaps from hobbyists who don't QT - this is the most common AEFW vector

What dips do (and don't) kill

The bottom line

Dip every Acropora. Look for eggs. Quarantine if possible. The 5 minutes of dipping prevents a 6-month eradication nightmare.