Acropora Eating Flatworm (AEFW)

🐛 Acropora Eating Flatworm (AEFW)

1. Name/Common Name

• Common Name: Acropora Eating Flatworm (AEFW)

• Scientific Name: Prosthiostomum spp. (exact species may vary)

2. Category

• Invertebrate Pest (Parasitic Flatworm)

3. Description

• Flat, oval body

• Beige, tan, or translucent with slight speckling

• Often undetectable until damage appears

4. What They Affect

• Primarily Acropora corals (especially smooth-skinned varieties like Acropora valida, A. millepora)

• Will not affect other SPS/LPS corals or fish

5. Size

• Adults: ~3–6 mm in length

• Eggs: ~0.5 mm, often laid in spiral or crescent-shaped clusters on dead coral skeleton

6. Reproduction Rate

• Moderate to high

• Egg-layers; hatching time ranges from 5–7 days

• No free-swimming larval stage, but rapid reinfestation is common

7. Contagiousness

• Very contagious among Acropora colonies

• Spread via frag swaps, contaminated tools, or coral dips

• Does not spread to non-Acropora

8. Symptoms/Signs

• Fading or paling tissue

• Bite marks or missing flesh, often starting at the base

• Heavy mucus production

• Tissue recession

• Brown flatworms seen detaching during dips

9. Environmental Triggers

• Often introduced through new coral additions without proper quarantine

• Thrive in nutrient-rich, high-flow environments but not dependent on them

10. Prevention

• Strict coral quarantine (minimum 4–6 weeks)

• Coral dips (e.g., Bayer, Revive) with visual inspection

• Frag racks in separate systems if possible

11. Treatment Options

• Coral dips (e.g., Bayer Advanced Insect Killer) to kill adult worms

• Manual removal of eggs (scraping or fragging affected base)

• Repeat dips every 5–7 days for 3–4 weeks (to target hatch cycles)

• Biological control: some wrasses (e.g., Halichoeres melanurus) may eat flatworms but aren’t reliable

• No in-tank medication is fully effective

• Remove and frag heavily infested colonies if necessary

12. Prognosis

• Can be managed and eradicated with persistence

• High reinfestation risk if eggs are missed

• Total tank infestation possible if not addressed early

13. Difficulty to Eliminate

• 🔥 High: due to egg resistance and stealthy adults

• Requires long-term commitment and sharp observation

14. Additional Notes

• Often confused with Planaria or Red Flatworms (but AEFW are Acro-specific and more destructive)

• Look for bite patterns and color loss in affected colonies

• Use white container for dips to better spot detached worms