Zoanthus Information

Zoanthus (Zoanthids) Complete Information & Care Guide

What are Zoanthus?

Zoanthus, also known as zoanthids or zoas, are among the most popular coral species in marine aquariums. These colorful soft corals are known for their vibrant colors, fast growth, and relatively easy care, making them ideal for both beginners and experienced aquarists.

Characteristics of Zoanthus

  • Appearance: Zoanthus grow in colonies of small polyps connected by a mat of tissue. Each polyp has tentacles surrounding a central mouth.
  • Colors: Available in virtually every color of the rainbow—from bright green and orange to purple, blue, and red. Some varieties have multiple colors in a single polyp.
  • Size: Individual polyps range from 0.5 to 2 cm in diameter, depending on the species.
  • Growth rate: Under optimal conditions, zoanthus can grow rapidly and form new polyps.

Care requirements

Relief

Zoanthus are flexible when it comes to lighting and can thrive under a variety of light intensities:

  • Low to medium light: Most zoanthus do well under 50-150 PAR
  • High Light: Some varieties can adapt to higher light intensities (150-250 PAR)
  • Acclimatization: Always start with lower light intensity and increase gradually to prevent bleaching

Water flow

Zoanthus prefer low to moderate water flow:

  • Provide sufficient flow to remove detritus from the colony
  • Avoid direct, strong currents that may damage the polyps
  • Indirect, wavy flow is ideal

Water parameters

Maintain stable water values ​​for optimal health:

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

Power supply

Although zoanthus contain zooxanthellae and obtain energy from light, they also benefit from supplementary feeding:

  • Light nutrition: Primary energy source via photosynthesis
  • Supplementary feeding: Optional but beneficial - small particles such as phytoplankton, zooplankton or special coral food
  • Frequency: 1-2 times per week if desired
  • Method: Target feeding with a pipette or general feeding during low flow

Placement in the Aquarium

  • Zoanthus can grow on rocks, substrate or even on the aquarium glass
  • Allow sufficient space between different coral species to prevent chemical warfare
  • Place them on stable surfaces where they can adhere
  • Keep their growth potential in mind – they can spread quickly

Fragmentation and Propagation

Zoanthus are excellent for fragmentation:

  • Cut off a group of 3-5 polyps with sharp scissors
  • Attach the fragment to a new stone with coral glue or elastic
  • Place in an area of ​​low flow until the fragment is attached
  • Fragments usually grow quickly into new colonies

Common Problems

Polyps remain closed

Possible causes:

  • Poor water quality
  • Too much or too little light
  • Insufficient flow
  • Chemical warfare with other corals
  • Stress due to recent move

Loss of color

Possible causes:

  • Too much light (bleaching)
  • Nutrient deficiency
  • Unstable water parameters

Slow growth

Possible causes:

  • Insufficient lighting
  • Low nutrient values
  • Insufficient flow

Safety advice

IMPORTANT: Zoanthus contain palytoxin, one of the most toxic substances in nature. Always take the following precautions:

  • Wear gloves when handling zoanthus
  • Avoid contact with open wounds
  • Wash hands thoroughly after contact
  • Wear safety glasses in case of fragmentation
  • Work in a well-ventilated area
  • Keep pets and children away during maintenance

Conclusion

Zoanthus are fantastic corals for any reef aquarium. With their beautiful colors, relatively easy care, and rapid growth, they bring life and color to your tank. By following the correct care guidelines and observing safety precautions, you can enjoy these beautiful corals for years to come.
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