Zoanthus (Zoanthids) Complete Information & Care Guide

• Zoanthus, often called "zoas," are colorful, colony-forming soft corals that are extremely popular in the reef hobby. Their bright colors, unique patterns, and strong growth potential make them suitable for both beginners and experienced reefers. Thanks to their flexibility in light, flow, and water parameters, they fit well in virtually any reef aquarium, from nano-reef tanks to large systems.

What are Zoanthus?

• Zoanthus are a group of soft corals consisting of small polyps that grow in colonies.

• Each polyp is attached to a common base (mat), allowing them to spread quickly over rocks, plugs and frag plates.

• They come in countless color variations from pastel to neon and many variants are very popular with collectors worldwide.

Key Features

• Type: soft coral (zoanthid)
  
• Growth: colony-forming, can expand quickly
  
• Difficulty level: easy to medium
  
• Polyp size: several millimeters to ±1 cm
  
• Colors: extremely diverse (neon, metallic, pattern variations)
  

Recommended water values

• Zoanthus are quite forgiving, but color and growth improve when water parameters are stable.

Parameter ideal value

• temperature 24–25.5 °C

• Salinity 1.024–1.026 (≈35 ppt)

• pH 8.0–8.3

• Alkalinity (KH) 8–10 dKH

• Calcium 380–420 ppm

• Magnesium 1200–1350 ppm

• Nitrate 0–10 ppm

• Phosphate 0.03–0.07 ppm

• Tip: Zoanthus like stability . Rapid fluctuations can cause polyps to close.

Lighting requirements & placement

• Zoanthus are versatile and can survive in low, medium, and high light. However, their color can change significantly depending on the intensity.

Light

• Perform excellently under full spectrum LED lighting.
  
• Start new frags lower in the tank and move them up when they stay comfortably open.
  
• Too much light can shrink or bleach polyps.
  
• Too little light can cause tanning.
  

Placement

• Place on rocks, fragplugs or fragplates.
  
• Leave space around the frag for expansion.
  
• Ideal for creating colorful “zoa gardens”.
  

Current

• Good water flow helps keep the polyps clean and ensures healthy growth.

Ideal:

• Light to moderate, variable current
  
• Just enough to keep dirt out, but not so strong that the polyps collapse
  

Power supply

• Zoanthus are primarily photosynthetic thanks to their symbiotic zooxanthellae. Supplemental feeding isn't necessary, but it can be beneficial.

Optional nutrition (for better growth & color):

• Fine plankton food
  
• Amino acids
  
• Microfauna (such as rotifers or fine zooplankton)
  
• Reefbooster or similar products
  

Always feed sparingly to avoid nutrient peaks.

Maintenance & care

A healthy aquarium is the basis for strong growing zoanthids.

Regular maintenance

• 10–25% water change every 2–4 weeks
  
• Test alkalinity, calcium and magnesium regularly
  
• Keep glass, rock and plugs free of algae
  
• Remove detritus around the colonies
  
• Inspect regularly for pests and parasites
  

Be careful when combining with certain fish or invertebrates

• Some fish (such as angelfish) may sip on zoas, but they are generally left alone.

Common problems

Close polyps

Could be caused by:

• Too strong current
  
• Suddenly strong light
  
• Unstable water values
  
• Bullying or nudibranchs
  
• Algae between the polyps
  

Discoloration or mucus

Usually caused by:

• Poor water quality
  
• Not enough current
  
• Infections
  

Predators

The most well-known threats are:

• Zoa nudibranchs
  
• Predatory snails
  
• Aiptasia among the colonies
  

Regular dipping and checking helps prevent many problems.

Safety – Important!

• Some Zoanthus species may contain palytoxin , one of the most potent natural toxins. While the risk is small, caution is crucial.

Safety instructions:

• Always wear nitrile gloves when handling.
  
• Wear safety glasses when handling or moving.
  
• Never rub your face while working.
  
• Work in a well ventilated area .
  
• Rinse immediately with water in case of contact with skin.
  
• In case of irritation: seek medical advice.
  

Careful handling completely prevents risks.

Why Zoanthus Are a Top Choice

• Huge color range
  
• Rapid growth
  
• Relatively easy
  
• Perfect for nano tanks
  
• Suitable for beginners and collectors
  
• Ideal for colorful “zoa gardens”
  Zoanthus Information