Fig. 1. A healthy colony of polyps of the genus Zoanthus (Hexacorallia: Zoanthidae).
Anecdotes of this illness began to emerge on web forums in the early part of the 2010s whose aetiology was poorly understood, so the author thought it time to implement a literary review with an aim of furthering his previous comprehension. Aquarists have successfully mitigated this ailment with aquarium-approved chemotherapies formulated as bactericides for the genus Pseudomonas (Heidi 2011; MyNemesis 2011). We must first, however, raise awareness of the real threat to human health posed by the toxins liberated by its favorite hosts.
Zoanthid Palytoxin
Polyps classified in the family Zoanthidae manufacture palytoxin where fever, chills, muscle aches (myalgias), and a shortness of breath (dyspnoea) that develops into a potentially-lethal non-productive cough, typically follow exposing cuts or grazes, aerosol inhalation, or the ingestion of polluted water, polyp mucus, or contaminated shellfish (Sand et al. 2015).
A man and his family were poisoned when he cleaned Zoanthus polyps under running hot water, because stress triggers the excretion of surplus mucus and defense compounds. The patient suffered tachycardia at 112 beats per minute as well as elevated temperature and blood pressure and at some point, developed acute lung damage during his seven-day hospitalization (Sand et al. 2015).
Zoanthus Taxonomy
Animals of the genus Zoanthus are ranked in the phylum Cnidaria, the class Anthozoa, the subclass Hexacorallia, the order Keywords: reef aquarium, palytoxin, successful treatment, zoa pox, family Zoanthidae, Zoanthus polyps.
Handling Zoanthus
The author and his employees have acclimated, cultured, and packaged Zoanthus polyps in commercial environments for numerous years without precaution and mishap, albeit here, he recommends avoiding wound exposure and wearing a facemask, gloves, and safety glasses. Do not stress colonies and purge mucus from skin with thorough rinsing and gentle rubbing.
Fig. 2. Acute zoa pox. Image courtesy of Peter Hughes ©, Southampton, UK.
Symptoms
Polyps close and liquefy but not before their stalks develop yellow pimples, which is a rare example of extraordinary host fidelity insomuch as members of the genus Palythoa are not affected (Figs 2. to 4.).
A search on Google Scholar indicated that the scientific community has not undertaken studies of this disease. We are thus limited to hearsay and grey literature. In the interests of objectivity, it was therefore impossible to further enlighten over and above what is described herein.
Be that as it may, gram negative bacteria of the genus Pseudomonas are significant nitrifiers of the microbial consortium of a saltwater biofilter, that perform best in the laboratory (in vitro) using a growth medium supplemented with a salt of ammonium (Cowan 1974; Tal et al. 2003). They ostensibly participate in denitrification (Colasanti 2011) whilst many manufacture an arsenal of protein-degrading proteases which may represent virulence factors used during disease-causation (pathogenesis; Herbert 1999). However, Roberts maintained that members of this genus are non-fermentative aerobes that respire oxygen (Roberts 1989). A handful of species and strains are conspicuous pathogens of animals (Noga 2010) like P. fluorescens that cause piscine bacterial haemorrhagic septicaemia, whereas Japanese eels (Anguilla japonica) can suffer from red spot disease elicited by P. anguilliseptica (Roberts
1989). Moreover, some species manufacture yellow pigments, whereas P. aeruginosa generate rainbow-like patterns on the surface of bacon (Cowan 1974a) which are rendered harmless when properly cooked.
Fig. 3. Button polyps of the genus Palythoa (Hexacorallia: Sphenopidae) do not develop zoa pox.
Fig. 4. The cause of zoa pox remains unclear. Image courtesy of Peter Hughes ©, Southampton, UK
The author has no firsthand experience of this illness despite trading in too numerous to quantify zoanthids, and there were no reports or sightings of this disease before he closed The Reef Ranch (TM). New illnesses do materialize whilst reefing trends and practices remain exceedingly changeable. Could it be that recent parasitic loads and the advent of coral dips have somehow contributed. A coral’s mucosal microbiome is the colonies first line of defense and even those formulated from natural ingredients
are meant to stimulate surplus mucus and a sloughing of these vital microbial communities. Aquarists have dipped corals in a dilute solution of Lugol’s iodine long before the first reports of this illness, which comprises beneficial as well as molecular iodine that is corrosive and hostile to all life. The author recalls weighing molecular iodine (I2) which is a remarkable deep purple fuming crystalline halogen on a laboratory balance in an extraction cabinet with a pure nickel spatula, which to his surprise and horror, it dissolved.
Grey literature suggests that immersion in a solution of around 2 milliliters (ml; ~40 drops) of Lugol’s iodine in a US gallon (380 ml) of aged aquarium water for 15 minutes (reef2reef.com; 3reef.com; nano-reef.com) will cure this illness (Ricklalonde 2010). Sterilizing the mucus layer of corals will leave them vulnerable to microbial attack, yet the virulence of zoa pox appears to demand a “kill or cure” approach. Preferably dip new outwardly healthy zoanthids in dilute solutions of Coral RX Pro or ReVive Coral Cleaner but if from a reputable supplier that openly discusses the control of pests and parasites, it would be imprudent to stress colonies.
Ensure your husbandry and system are optimized by consulting open-access Coral Nubbins: Reef Troubleshooting at https://reefranch.co.uk/ as less than ideal conditions can predispose corals to ailments that they might ordinarily withstand.
Control
API Furan-2TM has proven efficacious as a colonial dip which contains the Pseudomonas antimicrobial, nitrofurazone as well as methylene blue. Likewise, Jungle Fungus Clear is formulated from nitrofurazone and potassium dichromate, all of which may be unavailable or banned, and thus adhere to national legislation. Submersion in a dilute solution of either therapeutic will be stressful and will likely elicit the excretion of palytoxin, whilst neither of these remedies should be administered to reef aquaria.
Dissolve three 8-oz sachets of Furan-2TM in three cups of aged tank water and dip the coral for 25 minutes (Heidi 2011; MyNemesis 2011). Peter Hughes observed partial efficacy with this preparation and advised multiple treatments (Hughes, personal communication) and thus re-immerse on the seventh and 14th day (Heidi 2011; MyNemesis 2011).
Thoroughly purge these compounds including iodine from corals before reintroducing them to a system by immersing them in two consecutive vessels filled with just aged seawater. Use a turkey baster in the second to jet water at the colony and exploit prerinsed reef-grade granular activated carbon (GAC) in the aquarium’s filtration for 48 hours, and / or place recuperating polyps in quarantine.
References
Colasanti M (2011) Aquarium Chemistry: The Nitrogen Cycle: New Developments and New Prospects. AdvancedAquarist.com. https://www.advancedaquarist.com/2011/4/chemistry
Aslett, C., G. (2025) Coral Nubbins: Reef Troubleshooting. https://reefranch.co.uk/
Cowan ST (1974) Cowan & Steel’s Manual for the Identification of Medical Bacteria, Second Edition. Cowan, S., T. (ed.). Cambridge Univesoty Press, Cambridge, Great Britain. p 31.
Cowan ST (1974a) Cowan & Steel’s Manual for the Identification of Medical Bacteria, Second Edition. Cowan, S., T. (ed.). Cambridge Univesoty Press, Cambridge, Great Britain. pp 90-93.
Heidi (2011) Killing Zoa Pox! (The Furan-2 method). CaptiveReefs.com. http://www.captivereefs.com/forum/basics/killing-zoa-pox-furan2-method-17724/#.X3cqB3lKjb1
Herbert RA (1999) Nitrogen cycling in coastal marine ecosystems. FEMS Microbiology Reviews. 23(5), 563-590.
MyNemesis (2011) Killing Zoa Pox! (The Furan-2 method). CaptiveReefs.com. http://www.captivereefs.com/forum/basics/killing-zoa-pox-furan2-method-17724/#.X3cqB3lKjb1
Noga EJ (2010) Fish Disease: Diagnosis and Treatment, Second Edition. Noga EJ (ed.). John Wiley & Sons Inc. p 212t.
Ricklalonde (2010) Zoa Pox – Advanced Information. TheFragTank.ca. https://thefragtank.ca/community/threads/zoa-pox-advancedinformation.6470/
Roberts RJ (1989) Fish Pathology 2nd Edition. Bailliere Tidal, 24-28 Oval Road, London. p 300.
Sand M, Hall C, Levy D & Sattler S (2015) A Case of Palytoxin Poisoning in a Home Aquarium Enthusiast and His Family. Case Reports in Emergency Medicine. 2015, 621815.
Tal Y, Watts J, Schreier S, Sowers K & Schreier H (2003) Characterization of the microbial community and nitrogen transformation processes associated with moving bed bioreactors in a closed recirculated mariculture system. Aquaculture. 215(1), 187-202.
WoRMS (2020) World Register of Marine Species. Zoanthidae Rafinesque, 1815.
http://www.marinespecies.org/aphia.php?p=taxdetails&id=100690
For more information, visit https://reefranch.co.uk/
