Pests & Problems

Identify the pest. Understand your next step.

A visual library of coral pests, with practical guides to identification, containment and treatment.

Acropora

Acropora-Eating Flatworm (AEFW)

Recognise flatworms, bite marks and egg clusters on Acropora.

Acropora

New Acropora-Eating Flatworm

Spot small dark flatworms and scattered pale eggs on Acropora.

Flatworm beneath a torch coral head beside the flesh band, Reef Builders 2020

Euphyllia

Euphyllia-Eating Flatworms

Inspect torches, hammers and frogspawn for worms and eggs.

Acropora

Acropora Parasitic Copepods

Recognise red, white and black bugs under magnification.

Drupella snails feeding in an aggregation across a branching staghorn Acropora colony.

Acropora · Other corals

Coral-Eating Snails — Drupella

Identify coral-eating snails, feeding damage and egg capsules.

Montipora

Montipora-Eating Nudibranchs

Check feeding margins and undersides for nudibranchs and eggs.

Goniopora

Goniopora-Eating Nudibranchs

Recognise nudibranchs and coiled egg ribbons on Goniopora.

AI-generated reconstruction of a sea spider on zoanthids. Anatomy awaiting independent verification.

Zoanthids · Other corals

Sea Spiders

Find sea spiders hidden between polyps and beneath coral tissue.

Aeolidiopsis ransoni laying a folded egg ribbon, M Nishina 2002

Zoanthids

Zoanthid-Eating Nudibranchs

Look for camouflaged nudibranchs and folded egg ribbons.

The original Aiptasia photograph: Exaiptasia diaphana with its slender translucent tentacles.

All coral groups

Aiptasia and Majanos

Distinguish pest anemones and compare targeted control options.

Image credits and sources

AEFW identification photograph: Jonathan Barton, in Grimm, Barton, Bourne, Sato & Doyle (2026), Figure 1. Original publication; CC BY 4.0. Isolated specimen panel cropped for the card.

New flatworm library image: Reef Builders (2019), “Is This a NEW Acro Eating Flatworm?”, article by Jake Adams. Cropped for the library card; the guide displays the full original photograph.

Red bug identification figure: Christie and Raines (2016), reproduced in Cardoso et al. (2026), Figure 3. Source and original figure. Cropped to fill the card image panel. Third-party image publication permission remains unconfirmed; retained in this unpublished draft for review.

Drupella feeding aggregation: ConserveMarine, Koh Tao, Thailand, 30 August 2010. Original photograph; CC BY-SA 4.0. The card crop remains under the same licence.

Montipora nudibranch card: adapted from Wang A., Conti-Jerpe I.E., Richards J.L. & Baker D.M. (2020), ZooKeys 909, Figure 1. Original photograph and authors; CC BY 4.0. Cropped; research arrows, circles and scale annotation removed with AI-assisted editing. The full annotated source remains in the Montipora guide. Adapted image for visual orientation; refer to source photographs for anatomical detail.

Goniopora nudibranch card: AI-generated photoreal reconstruction based on Phestilla gonioporae morphology documented by Hu, Zhang, Yiu, Xie & Qiu (2020). Shows a nudibranch, affected Goniopora tissue and an orange egg ribbon. This is an illustration, not a specimen photograph; exact anatomy is not independently verified.

Sea-spider card: AI-generated photoreal reconstruction of a pycnogonid on zoanthids, based on real specimen morphology. This is an illustration, not a specimen photograph. Exact anatomy is not independently verified.

Zoanthid nudibranch library photograph: M. Nishina (2002), Sea Slug Forum, Australian Museum, Aeolidiopsis ransoni laying eggs. Cropped for the card; the guide retains the full original photograph. Publication permission remains unconfirmed; included in the unpublished draft for review.

Aiptasia photograph: Chris Alice Kratzer, Exaiptasia diaphana. Original photograph; CC BY-SA 4.0. The card crop remains under the same licence.