Montipora Eating Nudibranch

🐛 Montipora Eating Nudibranch (MEN)

1. Name/Common Name

• Common Name: Montipora Eating Nudibranch (MEN)

• Scientific Name: Likely Phestilla spp. (still debated in the hobby)

2. Category

• Invertebrate Pest (Corallivorous Nudibranch)

3. Description

• Small, white to translucent nudibranch with branching cerata (feathery appendages on its back)

• Often mimics the texture/color of Montipora tissue

• Larvae are even more translucent and hard to detect

4. What They Affect

• Montipora species only, especially plating (M. capricornis) and encrusting types

• Some preference for lighter-colored Montis

5. Size

• Adults: ~2–4 mm long

• Eggs: tiny white spirals, often on undersides or edges of Montipora plates

6. Reproduction Rate

• High

• Lays egg spirals daily

• Lifecycle: 3–7 days from egg to feeding nudi under optimal conditions

7. Contagiousness

• Highly contagious among Montipora species

• Spread through frag swaps, coral mounts, or overlooked egg masses

• Will not affect Acropora or other SPS

8. Symptoms/Signs

• Pale or bleached edges of Montipora

• Tissue loss in patches, starting at edges or shadowed areas

• Eggs often seen in white spirals on underside

• Nudibranchs visible under close inspection or during dips

9. Environmental Triggers

• Introduced via unquarantined frags

• Thrive in stable, warm tanks (but can survive dips)

• Egg masses can be overlooked, making them persistent

10. Prevention

• Strict quarantine of all Montipora for at least 4–6 weeks

• Visual inspection and dipping (e.g., Lugol’s iodine, CoralRx, Bayer)

• Use of frag racks or isolation containers during quarantine

• Scrub frag plugs and bases to remove eggs

11. Treatment Options

• Frequent dips (every 4–5 days) to kill adults as they hatch

• Manually remove eggs between dips (scraping, brushing)

• Fragging infected sections can save colonies

• Biological control: some wrasses (e.g., Six-line, Melanurus) may eat them, but not reliable

• Full removal of infected Montipora may be necessary in advanced cases

12. Prognosis

• Manageable if caught early

• Eggs are resistant to dips, so diligence is key

• Left untreated, they can wipe out all Montipora in a system

13. Difficulty to Eliminate

• 🔥🔥 High: due to small size, egg resilience, and rapid lifecycle

• Persistence and observation required over several weeks

14. Additional Notes

• Often confused with harmless small nudibranchs or flatworms

• Using a turkey baster can blow nudis off the coral for better visibility during inspection

• Keeping Montipora separate in a frag tank during treatment helps control spread