Rigid Branching Hydnophora Care Guide

Rigid Branching Hydnophora (Hydnophora rigida) is a LPS coral. Care covers 100-200 PAR, medium-high flow, reef parameters and feeding; intermediate level.

Overview

Rigid Branching Hydnophora (Hydnophora rigida) is a LPS coral in the family Merulinidae. Branching Hydnophora with thick stalks. Often considered LPS-SPS hybrid; aggressive sweepers.

Taxonomy

Family: Merulinidae
Genus: Hydnophora
Scientific name: Hydnophora rigida
Common synonyms: Branching Horn Coral

Habitat

In the wild, Hydnophora rigida is reported from Indo-Pacific, where it occupies mid to lower reef slopes and lagoons (typically 5-30 m). The species adopts a branching growth form on hard substrate within zooxanthellate reef communities.

Tank requirements

Salinity (specific gravity): 1.024-1.026
Temperature: 24-26 °C (75-79 °F)
pH: 8.1-8.4
Carbonate hardness (dKH): 8-11
Calcium: 400-450 ppm
Magnesium: 1280-1350 ppm
Phosphate (max): 0.03 ppm
Nitrate (max): 5 ppm
Minimum system age: 3 months

Placement and lighting

PAR (placement zone): 100-200 PAR
Water flow: medium-high

Mount this LPS coral on the lower or mid rockwork or on the sand bed (for free-living forms) where light is moderate. Strong direct flow can damage the fleshy tissue; aim for indirect, varied movement.

Feeding

Hydnophora rigida hosts symbiotic zooxanthellae and derives most of its energy through photosynthesis. Additional feeding is generally not required when lighting is adequate.

Compatibility

This coral is very-aggressive toward neighbours. It extends sweeper tentacles capable of stinging adjacent corals, so leave generous spacing (10-20 cm) between colonies. Reef-safe with most fish and invertebrates.

Care notes

Difficulty level: intermediate. Reported skeletal growth in well-tuned reef tanks is approximately 0.3-0.7 cm/month. Propagation by fragmentation is straightforward for branching colonies — separate branches or polyps with a bone cutter, glue to plug, allow 1-2 weeks for healing. Maintain stable alkalinity (avoid swings above ±0.5 dKH per day) to preserve tissue health.