Zoanthid Care Guide: Species, Morphs, Placement & Palytoxin Safety

Q: Are zoanthids good for beginners?

Yes — zoanthids are widely considered the best beginner coral. They tolerate alkalinity from 8–12 dKH, don't require precise calcium/magnesium dosing, survive parameter swings, and thrive under basic LED lighting. Bulk Reef Supply specifically recommends an all-zoa garden as a first reef tank build.

Q: Do all zoanthids contain palytoxin?

No — palytoxin is primarily produced by Palythoa and some Protopalythoa species. Zoanthus species generally do not produce palytoxin or produce it in negligible amounts. However, it is impossible to visually confirm whether a specific specimen contains palytoxin, so you should treat every zoanthid as potentially toxic and always wear gloves and eye protection when handling them.

Q: What PAR do zoanthids need?

Zoanthids thrive in a broad PAR range of 80–200, with the sweet spot being 100–150 PAR for most morphs. Bright neon morphs that were grown under high light may need 150+ PAR to maintain color. Start new zoanthids at lower PAR and move them higher over 2–3 weeks to acclimate.

Q: Should I dip zoanthids before adding to my tank?

Absolutely yes. Always dip new zoanthids in a coral pest dip (Coral Rx, Bayer insecticide dip, or Revive) for 5–10 minutes before introducing them to your display tank. This removes zoanthid-eating nudibranchs, sundial snails, flatworms, and other hitchhikers. Wear gloves during the dip. For extra safety, quarantine new zoanthids for 2–4 weeks with weekly dipping.

1. What Are Zoanthids?

Zoanthids (order Zoantharia) are colonial soft coral polyps found throughout tropical and subtropical oceans. Unlike stony corals, they lack a hard calcium carbonate skeleton — instead, individual polyps are connected by a shared tissue mat called the coenenchyme that spreads across rock surfaces [1]. Each polyp is a small anemone-like organism with a central oral disc surrounded by two rings of tentacles.

In the reef aquarium hobby, “zoas” and “palys” are among the most collected corals, with hundreds of named color morphs driving a vibrant collector market [2]. They are widely considered the best beginner coral because of their hardiness and tolerance for imperfect water conditions [3].

Three Genera You’ll Encounter

Zoanthus

Smaller polyps (3–10 mm oral disc)
Brightly colored — green, orange, red, blue, yellow
Polyps on distinct stalks
Does NOT incorporate debris into tissue [4]
Most named morphs are Zoanthus

Palythoa

Larger polyps (10–20 mm disc)
Brown, green, cream — less vivid
Polyps embedded directly in mat
Incorporates sand and debris for structure [4]
Contains palytoxin [9]

Protopalythoa

Large polyps on stalks (not embedded)
Longer tentacles, larger oral disc
Colorful disc under actinics
Molecular studies suggest it may be the same genus as Palythoa [4]
Also contains palytoxin

Taxonomy note: Molecular phylogenetic analysis found only 0.0–0.1% genetic divergence between Palythoa and Protopalythoa, strongly suggesting they are the same genus [4]. In practice, hobbyists use “zoa” for small Zoanthus morphs and “paly” for larger Palythoa/Protopalythoa types.

2. Tank Requirements

Zoanthids are among the hardiest corals in the hobby. They tolerate parameter swings that would stress SPS corals, making them an excellent choice for beginners and nano tank keepers [3]. That said, stable conditions still produce the best growth and coloration.

Parameter	Target Range	Notes	Source
Temperature	76–80°F (24–27°C)	Stable > precise number	[5]
Salinity (SG)	1.024–1.026	1.025 ideal	[5]
Alkalinity (dKH)	8–12	Very forgiving; stable matters most	[5] [3]
Calcium (ppm)	380–440	Not heavy consumers	[5]
Magnesium (ppm)	1250–1350	Standard reef levels	[5]
pH	8.0–8.3	Standard range	[5]
Nitrate (ppm)	5–25	Tolerate higher than SPS	[3]
Phosphate (ppm)	0.03–0.10	Some nitrate/phosphate improves color	[3]

Beginner-friendly: Unlike SPS corals that demand alkalinity stability within ±0.3 dKH, zoanthids can handle dKH swings of 1–2 points without visible stress [3]. They also don’t heavily consume calcium or alkalinity since they lack calcium carbonate skeletons. Regular water changes are usually sufficient — no dosing pump required.

3. Lighting & Placement

Zoanthids are remarkably flexible with lighting, thriving across a wide PAR range. However, their color history matters — a zoanthid grown under intense light at a coral farm may bleach or brown out if suddenly placed in a dim corner [6].

PAR Range	Zone	Best For	Source
80–120 PAR	Lower tank / shaded	New acquisitions, acclimation, palythoa	[6]
120–150 PAR	Mid-tank	Most zoanthids — sweet spot for color + growth	[6] [1]
150–200 PAR	Upper-mid	High-light morphs (bright neon varieties)	[6]

Placement Tips

Mid-tank is the safe default. Place new zoanthids in the middle third of the tank where PAR is typically 100–150 [6].
Acclimate slowly to light. Start low and move up over 2–3 weeks. Sudden light increases cause polyps to stay closed or bleach [1].
Bright morph = likely high light origin. Neon green, orange, and red morphs often come from high-PAR farms. They may need 150+ PAR to maintain their color [6].
8–12 hour photoperiod is recommended. Zoanthids benefit from a consistent day/night cycle [1].
Blue actinics pop zoanthid colors. Heavy blue spectrum (420–460 nm) makes fluorescent morphs glow, which is why zoanthid gardens often look best under actinic-heavy lighting [6].

Watch for signs of too much light: Polyps staying closed during the day, faded/bleached coloration, or shrinking disc size all suggest the zoanthid is getting more light than it wants. Move it lower or into a shaded area. [1]

4. Flow

Zoanthids prefer low to medium indirect flow. Too much direct current prevents polyps from fully extending, which reduces photosynthesis, feeding, and overall growth [1] [5].

Low–Medium

Ideal flow strength

Gentle sway, not pinned flat [5]

Indirect

Flow direction

Avoid blasting directly on colony [1]

Random

Pattern preference

Alternating/wave patterns work best [6]

Flow Guidelines by Polyp Size

Small-polyp Zoanthus (3–8 mm): Low to medium flow. These tiny polyps are easily overwhelmed by strong current and will stay closed [7].
Large-polyp Palythoa (10–20 mm): Medium flow. Larger polyps with sturdier tentacles can handle slightly more current [7].

The ideal look: Polyps should sway gently in the current with tentacles slightly moving. If polyps are pinned flat or flowing sideways like a flag, flow is too strong. If there’s zero movement and detritus accumulates on the colony, flow is too low [1].

5. Popular Morphs & Pricing

The zoanthid market revolves around named color morphs. Prices are driven by rarity, color complexity, growth speed, and hype — newer morphs command premiums that fall as propagation catches up with demand [2]. Below are representative price tiers per polyp.

Tier	Price/Polyp	Example Morphs	Notes
Common	$5–10	Eagle Eyes, Radioactive Dragon Eyes, Sunny D, Fire & Ice Zoas	Great starters, fast growers, widely available [2]
Mid-Range	$15–40	Purple People Eater, Fruit Loops, Bam Bam Orange, Miami Vice	Desirable colors, moderate availability [2]
Premium	$50–100+	Purple Hornet, Blueberry Field, Rastas, Mary Jane	Collector pieces, slower growers or unique patterns [2] [8]
Ultra	$100–500+	Nirvana, Gorilla Nipples, Utter Chaos, Grandmaster Krak, Stratosphere	Grail pieces, extremely limited supply, hype-driven [2] [8]

Market dynamics: Zoanthid prices are highly volatile. A morph that sells for $200/polyp when first introduced can drop to $20 within a year as hobbyists propagate and trade frags [8]. Conversely, “classic” morphs like Eagle Eyes and Dragon Eyes have stayed affordable for over a decade because they grow fast and are endlessly available [2].

What Makes a Morph Expensive?

Unique color combinations: Multi-colored oral discs with contrasting skirts and tentacles [8]
Slow growth rate: Less propagation = less supply = higher price [8]
Social media hype: A viral photo or video from a known collector can spike demand overnight [2]
Limited original source: Some morphs originated from a single wild colony [8]

6. Growth & Propagation

Zoanthids grow by budding new polyps at the edges of the colony. Growth is exponential — you start with 2 polyps, which become 4, then 8, then 16 [7]. Under ideal conditions, a fast-growing morph can add 4–6 new polyps per month, while slower varieties may produce just one new polyp every few weeks [7].

Fragging Zoanthids: Step by Step

1

Safety First

Wear gloves and eye protection at all times. Zoanthids — especially Palythoa — may contain palytoxin [9]. Work underwater or in a container of tank water to prevent aerosolization of toxin.

2

Close the Polyps

Gently agitate the colony so all polyps close. This makes it easier to see the connecting mat and plan your cuts [14]. You can also briefly turn off the lights.

3

Cut the Mat

Using a razor blade or bone cutters, slice through the coenenchyme between polyp groups. For rock-attached colonies, use stony coral cutters to chisel the polyps off with a small piece of rock attached [14]. Cut as little tissue as possible.

4

Dip in Iodine

Briefly dip the new frag in an iodine-based coral dip (like Lugol’s solution). This promotes healing and kills hitchhiker pests [14].

5

Attach to Plug

Glue the frag to a frag plug or rubble rock using reef-safe cyanoacrylate (super glue gel). If polyps detached without substrate, place them in a small container with coarse sand in low flow — they will naturally encrust onto the sand [14].

6

Recovery

Place frags in a low-light, low-flow area for 3–5 days. Most zoanthid frags fully recover and reopen within a week [7].

Critical safety reminder: Always frag zoanthids underwater. Never scrape, boil, or microwave rocks with zoanthids attached. Heating Palythoa releases palytoxin vapor, which has caused documented hospitalizations [9] [10]. See Section 8 for full safety details.

7. Feeding

Zoanthids are photosynthetic — they get most of their energy from symbiotic zooxanthellae algae. However, targeted feeding accelerates growth and enhances color [5]. It’s optional but recommended for anyone wanting to grow colonies faster.

How to Feed

Use a small particle coral food such as Reef-Roids, Coral Frenzy, or Benepets [7].
Target feed with a pipette or turkey baster. Squirt a small amount directly over the polyps while they’re open. You’ll see tentacles curl inward to capture the food [5].
Feed 1–3 times per week. Reef Chasers recommends at least 1–3 feedings per week with small-particle coral food [5].
Turn off flow pumps for 10–15 minutes during feeding so food settles on the polyps instead of being swept away.
Less is more. Overfeeding pollutes the water and raises nitrate/phosphate. A light dusting is better than a cloud of food [3].

Observation tip: Feed during the evening when polyps are fully extended and actively catching food particles. Many zoanthids open wider at dusk, which makes feeding more effective [1].

8. Palytoxin Safety

CRITICAL SAFETY WARNING: Palythoa and some Protopalythoa zoanthids produce palytoxin (PTX), one of the most toxic non-protein substances known to science. There is NO ANTIDOTE. Treatment is supportive care only. Multiple documented cases have resulted in hospitalizations and ICU admissions [9] [10]. Every zoanthid keeper must understand these risks.

What Is Palytoxin?

Palytoxin is a complex polyketide toxin produced primarily by Palythoa species. It was first isolated from the Hawaiian zoanthid Palythoa toxica [10]. It acts by converting the cell membrane Na+/K+ ATPase pump into an open ion channel, causing uncontrolled ion flow across cell membranes — effectively disrupting every cell it contacts [10].

It is not possible to visually determine which zoanthids contain palytoxin. Not all Palythoa produce dangerous levels, but you should treat every zoanthid as if it does [11].

Exposure Routes

Dermal Contact

Toxin enters through cuts, abrasions, or mucous membranes on hands. Even a tiny open wound is sufficient [12].

Inhalation

Boiling, microwaving, or pouring boiling water on live rock releases palytoxin vapor. CDC documented Alaskan cases from this exact scenario [9].

Ocular Splash

Squirting tank water into eyes while handling zoanthids. Even indirect splashes have caused severe eye irritation and corneal damage [11].

Symptoms

Symptoms can appear within minutes to hours and progress rapidly [9]:

Flu-like: Fever, chills, muscle aches, weakness, fatigue
Respiratory: Coughing, chest tightness, wheezing, shortness of breath
Neurological: Metallic/bitter taste, numbness, tremors, ataxia
Gastrointestinal: Nausea, vomiting, abdominal cramps, diarrhea
Cardiac: In severe cases, heart rhythm disturbances [10]

Documented Incidents

Alaska, 2012–2014 (CDC Report)

Multiple patients hospitalized after cleaning aquariums containing zoanthids. One patient developed symptoms including bitter metallic taste, fever, weakness, cough, and muscle pain 7–8 hours after exposure [9].

England, 2019

A family of five from Shropshire was poisoned and hospitalized after cleaning a tropical aquarium containing Palythoa. All five family members required hospital treatment [10].

Multiple U.S. Cases

Two persons developed fever, tremors, weakness, and ataxia within hours of cleaning a fish tank containing zoanthids. Both were hospitalized [9].

Safety Rules — Non-Negotiable

ALWAYS wear nitrile or latex gloves when handling any zoanthid. Double-glove if you have cuts on your hands [11].
Wear eye protection (safety glasses or goggles) to prevent splashes [11].
Frag underwater only. Never let a broken zoanthid colony dry out or be exposed to air where toxin can become airborne [11].
NEVER boil, microwave, or pour boiling water on rocks with zoanthids. This aerosolizes palytoxin and can poison an entire household [9].
Work in a well-ventilated area when fragging or cleaning [11].
Wash hands thoroughly with soap and water after any contact, even with gloves [11].
If symptoms develop, go to the ER immediately. Tell medical staff you were exposed to palytoxin from a marine aquarium coral. There is no antidote — treatment is supportive [10].

9. Common Problems

Zoa Pox

Symptoms: Small white or yellow pimple-like pustules appear on the stalk and mat of the colony. Affected polyps may close or appear irritated [13].

Treatment: The traditional treatment is Furan-2 (nitrofurazone) in a quarantine container. Pop the cysts underwater with a needle, then place the coral in the medicated water for 6–8 hours [13]. Increase flow over the colony afterward to keep detritus from settling. Note: API Furan-2 may be hard to find; nitrofurazone powder is an alternative [13].

Prognosis: Zoa pox rarely kills an entire colony. Most recover with treatment or even without intervention if flow and water quality are good [13].

Zoanthid-Eating Nudibranchs

Symptoms: Polyps mysteriously closing or disappearing. The nudibranchs mimic the coloration of the zoanthids they eat, making them nearly invisible [13].

Detection trick: Close all polyps by disturbing the colony. Any “polyp” that remains open is likely a nudibranch camouflaging itself [13].

Treatment: Remove visible nudibranchs manually. Dip all zoanthids in a pest-control coral dip (Coral Rx, Bayer, or Revive). Repeat dipping weekly for at least 4 weeks to catch newly hatched nudis from eggs, which take 2–3 weeks to hatch [13].

Sundial Snails (Heliacus spp.)

Symptoms: Polyps not opening, visible tissue damage. These small, flat-shelled snails hide between zoanthid stalks during the day and feed at night [13].

Treatment: Manually remove them — pick them out and discard. They are most active at night; inspect with a flashlight after lights-out. Sundial snails primarily arrive on wild-collected colonies, so quarantine and dip all new acquisitions [13].

Zoanthids Not Opening

Common causes:

Too much flow: Polyps physically cannot extend against strong current [1]
Light shock: Sudden increase in PAR after purchase or moving the frag [6]
Film algae: A waxy film builds up on polyps; they will shed this layer over time [13]
Pest predation: Nudibranchs, sundial snails, or zoanthid spiders irritating the colony
Parameter shock: Newly purchased corals adjusting to different water chemistry

Fix: Move to a lower-light, lower-flow area. Check for pests with a flashlight at night. Dip in coral pest treatment. Give them 1–2 weeks to acclimate before worrying [1].

Algae Overgrowth on Colony

Symptoms: Hair algae, film algae, or cyanobacteria growing over the zoanthid mat, smothering polyps.

Treatment: Gently remove visible algae with tweezers or a soft brush. Increase flow slightly to discourage settling. Address root causes: reduce photoperiod, check phosphate/nitrate levels, and ensure clean-up crew (hermit crabs, snails) is adequate [3].

10. Frequently Asked Questions

Are zoanthids good for beginners?

Yes — zoanthids are widely considered the best beginner coral. They tolerate alkalinity from 8–12 dKH, don’t require precise calcium/magnesium dosing, survive parameter swings, and thrive under basic LED lighting [3]. Bulk Reef Supply specifically recommends an “all-zoa garden” as a first reef tank build [3].

Can zoanthids kill other corals?

Zoanthids can overgrow and smother neighboring corals as their mat spreads. They are considered semi-aggressive — they won’t sting like torch corals, but their spreading colonies will outcompete slower-growing corals for rock space [1]. Leave 2–3 inches of bare rock between zoanthid colonies and other corals, and trim the edges of fast-growing colonies periodically.

How fast do zoanthids grow?

Growth varies widely by morph. Fast growers like Eagle Eyes and Dragon Eyes can add 4–6 new polyps per month under ideal conditions. Slower varieties may produce only 1 polyp per month [7]. Growth is exponential — a colony doubles faster as it gets larger because more polyps are budding simultaneously. Target feeding with Reef-Roids and stable water parameters are the biggest growth accelerators.

Do all zoanthids contain palytoxin?

No — palytoxin is primarily produced by Palythoa and some Protopalythoa species. Zoanthus species generally do not produce palytoxin or produce it in negligible amounts [10]. However, it is impossible to visually confirm whether a specific specimen contains palytoxin, so you should treat every zoanthid as potentially toxic and always wear gloves and eye protection when handling them [11].

What PAR do zoanthids need?

Zoanthids thrive in a broad PAR range of 80–200, with the sweet spot being 100–150 PAR for most morphs [6]. Bright neon morphs that were grown under high light may need 150+ PAR to maintain color. Start new zoanthids at lower PAR and move them higher over 2–3 weeks to acclimate. An 8–12 hour photoperiod with heavy blue actinic spectrum brings out the best fluorescent colors [6].

Should I dip zoanthids before adding to my tank?

Absolutely yes. Always dip new zoanthids in a coral pest dip (Coral Rx, Bayer insecticide dip, or Revive) for 5–10 minutes before introducing them to your display tank. This removes zoanthid-eating nudibranchs, sundial snails, flatworms, and other hitchhikers [13]. Wear gloves during the dip. For extra safety, quarantine new zoanthids for 2–4 weeks with weekly dipping to catch nudibranchs hatching from eggs [13].

References

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