By Bob Goemans
Site Supported in Part by:


Hydnophora rigida

(Dana, 1846)

Velvet Horn Coral, Thorny Coral

Likely Reef Tank Suitable

Likely Fish-Only Tank Suitable

Range: Indo-West Pacific Ocean: Madagascar, Indonesia, Philippines, Fiji, Solomon Islands, Samoa, New Caledonia, and Great Barrier Reef.

Natural Environment: Inhabits a wide range of reef environments and usually seen at depths between 3 to 100 feet (1 - 30 m).

General Husbandry: Occasionally seen in the trade and highly aggressive!

Placement should not be within 6 - 8 inches (15 - 20 cm) of another coral. After the lights go out it extends long sweeper tentacles (3 inches (7.5 cm)), sometimes only acrorhagi or mesenterial filaments, that can kill or severely sting any animal it touches/close by/downstream.

Best placed where it will receive bright light and very good water movement.

Capable of producing its nutritional needs via photosynthesis, yet benefits from once or twice a week feedings of various plankton-like foods, such as Oyster eggs, cyclops, baby brine shrimp, Spirulina, enriched adult brine and mysis shrimp.

Maricultured specimens available.


    Kingdom: Animalia

    Phylum: Cnidaria

    Class: Anthozoa

    Subclass: Hexacorallia

    Order: Scleractinia

    Family: Merulinidae

    Genus: Hydnophora

FYI: In the wild, has extensive growths of irregular shaped somewhat flattened branches and generally cream or green.

Experience Level: Intermediate

Diet: Photosynthetic/Plankton feeder

Temperament: Aggressive

Aquarium Environment: Reef or fish-only aquarium

Coral Safe: With caution

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: 74 - 83°F (23 - 28°C)

Minimum Tank Size: 100 gallons

Lighting: PAR 400 - 500+

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.

 Hydnophora rigida (Velvet Horn Coral, Thorny Coral)
Photo © Bob Goemans
Hydnophora exesa Merulina ampliata
Return to Linking Page
Site Supported in Part by:
Eco Tech Marine