Zoanthids Coral Trouble Card
Coralkin honest saltwater & reef care · coralkin.com ⚠️ Safety first — read this
Some zoanthids/Palythoa carry PALYTOXIN — one of the most potent natural toxins known, and a danger to the keeper, not the tank. It's held in the coral's flesh, so simply having zoas is low-risk; the danger comes from DAMAGING a colony — fragging, scraping, scrubbing, and above all boiling or “cooking” rock with zoas on it (which can aerosolise the toxin). Always wear gloves and eye protection when handling or cutting zoas, never boil rock that has zoas on it, work with ventilation, keep them away from cuts/eyes/mouth, and if you're exposed — especially with any breathing trouble — call poison control or seek medical help immediately.
🔬 There's no vet for corals — diagnose the water & environment
Corals almost never need (or have) a vet. A struggling colony is a chemistry, lighting/flow, or pest problem you fix yourself. Work these Coralkin tools:
- Parameter target chart — the cited target ranges to compare your test against
- Water-test checker — read your numbers and see what's off
- Dosing calculator — correct alkalinity, calcium and magnesium safely, in small steps
- Coral placement, light & flow guide — confirm the spot suits this coral
📇 Fill this in now
🚨 Trouble signs now?
- Polyps staying closed for days — check flow (too strong?), recent light changes (too much, too fast?) and water quality.
- White pimples on the mat (“zoa pox”), or melting/receding tissue.
- Pests: zoa-eating nudibranchs (camouflaged to look like the zoas), sea spiders, or tiny snails — dip and inspect new frags.
- A whole colony rapidly “melting” — remove affected pieces (gloves!) and check parameters.
🚗 First things to check
✅ Do
- Test the full parameter set — salinity, alkalinity, calcium, magnesium, nitrate, phosphate and temperature — and compare to targets.
- Check the lighting and flow at this coral's exact spot.
- Look for pests and for irritation from aggressive neighbours.
- Check for recent changes — new livestock, a dosing change, a big water change.
⛔ Don't
- Don't reach for OTC “cures” or dose blindly.
- Don't change everything at once — stability matters more than any single number.
- Don't keep a badly-failing colony next to healthy ones without isolating it or fragging off the healthy tissue.
📋 This coral's targets
- Colony / form
- Encrusting mats of button-like polyps that spread across the rock over time.
- Lighting
- Low–moderate — roughly 75–250 PAR. Acclimate to bright light slowly (too much, too fast can shock them); colour is a rough guide to their light preference.
- Water flow
- Low-medium to medium — enough to keep detritus off the polyps, but not so strong they can't open.
- Placement
- Low-to-mid rockwork to start; you can move them higher as they settle.
- Temperature
- 75–82°F (24–28°C).
- pH
- 8.1–8.4.
- Specific gravity
- 1.023–1.026 (reef-standard ≈35 ppt).
- Other targets
- Softies are forgiving — they don't need the high, stable alkalinity/calcium stony corals demand, and they tolerate higher nutrients than SPS. Keep it stable.
- Feeding
- Mostly photosynthetic (light-powered); they'll also catch tiny foods, and occasional fine coral food can boost growth — but light is the main driver.
- Growth & spread
- Fast-growing and collectible — colonies spread across the rock. Easy to frag (with the safety precautions above).
- Natural range
- Indo-Pacific reefs (shallow, high-light zones).
🌸 A struggling coral is almost always telling you about its water, light, flow, or a pest — not an infection a vet can treat. Stabilise your parameters to target, confirm the light and flow suit this coral, and rule out pests and aggressive neighbours before changing anything drastic. Sudden swings are themselves a stressor.
❓ Work through
- Is a parameter off-target?
- Is the light or flow wrong for this coral?
- Any pests, or aggressive neighbours?
- What changed recently?