Tiny Zoanthid Predators: What to Inspect Before You Treat

Your zoanthids stopped opening. Could a small hitchhiker be involved? Maybe—but light, flow, debris, recent disturbances and water changes can produce similar symptoms.

Check these places

• Around polyp skirts and the base of the colony.
• Under frag plugs or along the rock immediately next to the polyps.
• On adjacent corals, especially new additions.
• During different lighting periods, using a flashlight or magnifier without handling unnecessarily.

A brief inspection cannot establish that every hitchhiker is absent. Any treatment decision should follow a supported identification and the specific product directions; this guide does not prescribe a dip or treatment. Not every small organism is harmful, so try to identify it before taking action.

Take a useful identification photo

Show a sharp close-up of the suspected organism **and** a wider image of the entire colony. Add notes about how long polyps have been closed and whether any new frags arrived recently.

**Safety:** Zoanthids and related palythoas may contain potent toxins. Do not boil, heat, pressure-spray, cut or scrub colonies casually. Follow safe aquarium handling practices and seek immediate medical advice for possible toxin exposure.

**Discussion:** Have you ever found a hitchhiker so small you needed magnification?

Sources and further reading

• CDC report on zoanthid-associated palytoxin exposure

Community education offers possible explanations and observation steps; it does not confirm a diagnosis.