Identify hitchhikers on your live rock and corals, and the parasites that turn up on marine fish. Search by common name or scientific name below.
Every entry carries one of our identification plates. Click a plate to open it full size, with anatomy, size, damage and treatment notes.
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Treatment & In-Depth Guides
This page is for identification. For full symptoms, causes, management and the treatments we stock, follow the guides below.
- Marine Fish Diseases, Identification and Treatment. Covers marine ich, marine velvet, brooklynella, flukes, uronema (scuticociliatosis), black spot disease, bacterial infections and fin rot, and HLLE, along with the medications we stock for each and the published literature behind it.
- Marine Algae, Types, Causes and What Eats Them. Diatoms, green film, hair and turf algae, bubble algae, cyanobacteria, dinoflagellates, bryopsis, derbesia, cladophora, turtleweed, dictyota and coralline, plus clean-up crew recommendations.
- Coral Dipping Guide. Dipping is the most effective way to stop most of the pests on this page from ever reaching your display tank.
- Marine Fish Quarantining at Home. Quarantine is the single best defence against the fish parasites listed above.
- Freshwater Pest & Parasite ID Guide. The freshwater equivalent of this page.
Clean-up crew and herbivores that help keep a reef in balance are listed in our Marine Invertebrates and Marine Fish collections. Treatments are in Fish Medication and Supplements.
Illustrations
Every identification plate on this page is our own artwork, drawn in house for the Nicks AOT education centre. Click any plate to open it full size.
A note on four names. The sea slug that eats clove polyps is reported in the hobby as a Dermatobranchus species and has not been pinned down to species, so we list it at genus level. Ball anemones arriving on tropical live rock are usually Pseudocorynactis, a corallimorph rather than a true anemone; Corynactis is the related genus more often found in cooler water. Bristle worms and fireworms are listed separately on purpose. Most bristle worms in a reef tank are harmless scavengers, while the bearded fireworm carries bristles that cause a painful skin sting, so it is worth being able to tell them apart before you put a hand in the tank. Reef flatworms are listed both as a group and as the specific red planaria that most people mean, because several unrelated flatworms turn up in reef tanks and the right response depends on which one you have.
Disclaimer
This guide is provided for general educational purposes only. It is not a substitute for professional veterinary or aquatic health advice, and we cannot guarantee outcomes. Identification from a photograph can be difficult, and tank conditions, species sensitivity and system design all vary. If you are unsure what you are looking at, please get in touch with our team before treating.