parasite · saltwater tank

AEFW (Acropora-Eating Flatworms)

AEFW (Amakusaplana acroporae) are tan flatworms ~3-5mm that feed exclusively on Acropora tissue. Bite marks appear as small white spots; advanced infestation strips tissue + leaves bare skeleton.

Reviewed by Fast Aquatics husbandry team · Updated May 2026
Severity: Critical for Acropora collections - can wipe out colonies in months

Symptoms

What causes it

Hitchhiked on un-dipped Acropora frags. Eggs are hard to dip off; flatworms can hide for weeks before symptoms appear.

Treatment options

Always treat in a separate quarantine tank.

Bayer Advanced dip cycle. Dip every 5 days for 4-5 cycles to break the egg-hatch cycle. Most reliable treatment.
Sixline / leopard wrasse predators. Some wrasses pick AEFW off Acropora over time. Long-term control rather than treatment.
Manual egg removal. Scrape brown egg clusters off the coral base after dipping. Reduces re-infestation rate.

Prevention

Dip every new Acropora frag for 5+ minutes in CoralRx or Bayer Advanced. Quarantine SPS in a separate tank for 30 days.

Frequently asked questions

What does AEFW (Acropora-Eating Flatworms) look like?

Small white bite spots on Acropora flesh. Tan flatworms visible after a turkey-baster blast. Tissue recession in patches.

What causes AEFW (Acropora-Eating Flatworms)?

Hitchhiked on un-dipped Acropora frags. Eggs are hard to dip off; flatworms can hide for weeks before symptoms appear.

How is AEFW (Acropora-Eating Flatworms) treated?

Bayer Advanced dip cycle: Dip every 5 days for 4-5 cycles to break the egg-hatch cycle. Most reliable treatment.

Can AEFW (Acropora-Eating Flatworms) be prevented?

Dip every new Acropora frag for 5+ minutes in CoralRx or Bayer Advanced. Quarantine SPS in a separate tank for 30 days.

How fatal is AEFW (Acropora-Eating Flatworms)?

Critical for Acropora collections - can wipe out colonies in months

Related

Browse the full disease database for 45 aquarium conditions with treatment protocols, or check the care library for prevention-focused husbandry guides. Use our symptom matcher to rank likely diseases from observed signs, the water parameter checker to diagnose related water-quality issues, or the QT timeline calculator to plan a treatment schedule.

Aquarium-keeping fundamentals

Whatever specific topic brought you here, four fundamentals govern long-term aquarium success: water quality, parameter stability, biological filtration, and species-appropriate husbandry. Skip any one and the others struggle to compensate.

Water quality: ammonia + nitrite at zero, nitrate under 30 ppm freshwater + 10 ppm reef. Test weekly with API or Salifert kits. Use our water parameter checker to score your readings against your tank type.

Parameter stability: stable wrong parameters beat fluctuating ideal parameters. Most fish tolerate a wide pH range if it's stable. Sudden swings of 0.4+ pH or 5+°F kill fish faster than chronic suboptimal values. Use temperature controllers (Inkbird) + automated dosing for consistency.

Biological filtration: the bacterial colony on your filter media + rock + substrate is the engine. Never replace all media at once. Use our filter turnover calculator to size correctly.

Species-appropriate husbandry: research adult size, territoriality, diet, and tankmate compatibility before purchase. Use our tank stocking calculator + compatibility guides.

Frequently asked questions

How long does an aquarium take to set up? 4-6 weeks for full cycling + first stocking. Use our cycle ETA calculator + how long does cycling take.

What's the best aquarium for beginners? 20-gallon long. Big enough for parameter stability, small enough for budget + space. See beginner picks.

How often should I do water changes? 25-30% weekly. See water change frequency Q&A + water change calculator.

Why does my fish keep dying? 5 leading causes: uncycled tank, wrong species pairings, no quarantine, undersized tank, neglected water-change schedule. See full diagnosis.

Related resources

Saltwater livestock · Freshwater livestock · Coral catalog · Care library · Q&A library (222) · Glossary (127) · Disease database (50) · Calculators (29) · Interactive tools (7) · Husbandry deep-dives · DIY projects · State legality directory