By Bob Goemans
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Family Zoanthidae

Zoanthus pacificus

Walsh & Bowers, 1971

Button Polyps, Sea Mat, Zoas

Likely Reef Tank Suitable

Likely Fish-Only Tank Suitable

Range: Central Pacific Ocean

Natural Environment: Inhabits rubble, rocky areas and reef flat surfaces in coastal bays and lagoons near the surfaces experiencing wave action.

General Husbandry: Forms small to large clumps of short tentacle polyps with oral disc often contrasting in color. May even develop a third color.

Easy to maintain if given strong light and excellent water movement.

Even though a photosynthetic species which supplies about 90%+ of its nutrition, occasional feedings with zooplankton-like foodstuffs may enhance growth.


    Kingdom: Animalia

    Phylum: Cnidaria

    Class: Anthozoa

    Subclass: Hexacorallia

    Order: Zoantharia

    Suborder: Brachycnemina

    Family: Zoanthidae

    Genus: Zoanthus

FYI: For far more general information about these corals, see my article titled 'Zoanthids - A Wide Range to Choose From' in the 'Article" section of this website.

There is a snail called the Box Snail/Sundial Snail that feeds upon zoanthus species. Remove when seen.

Also, there is a very small nudibranch, Aeolidiopsis harrietae, that feeds on zoanthus species, and can have the exact same coloring of the polyp it is feeding upon! Extremely difficult to see, and if polyps are tending to stay close, look for this pest and remove with tweezers. Hopefully, its presence will not affect other polyps by laying eggs that will hatch and thereby negatively affect other colonies of zoanthus species in the aquarium! If you want a photo of this pest, please contact me.

Also, the camelback shrimp will feed upon zoanthus species.

Experience Level: Beginner

Diet: Photosynthetic/Zooplankton feeder

Temperament: Peaceful

Aquarium Environment: Reef or fish-only aquarium

Coral Safe:Yes

Fish Safe: Yes

Invertebrate Safe: Yes

Acclimation Time: 30 minutes+

Aquarium Hardiness: Hardy

Calcium (Ca): 380 - 430 mg/l

Alkalinity: 2.5 - 3.0 meq/l

Phosphate (PO4): <0.05 mg/l

Magnesium (Mg): approx. 1350 mg/l (relate to specific gravity)

Strontium (Sr) 8 - 10 mg/l

Temperature Range: 72 - 82°F (22 - 27°C)

Minimum Tank Size: 30 gallons

Lighting: PAR 400+

Water Movement: WM 2 - 3

Specific Gravity: 1.023 - 1.025

pH: 8.0 - 8.4

Iodine/Trace Elements Monitor/as necessary to maintain quality seawater.

 Zoanthus pacificus (Button Polyps, Sea Mat, Zoas)
Photo © Bob Goemans
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