Hydnophora grandis Propagation Guide
Propagating the larger-polyp branching Hydnophora grandis: dividing branches, healing frags, and respecting its aggressive chemical and sweeper-tentacle warfare.
Overview
Hydnophora grandis is a branching large-polyp stony coral of the family Merulinidae, recognized for noticeably larger polyps than the thinner-branched H. rigida. Like its relatives it grows as discrete branches, which is the trait that allows it to be propagated by simple division.
Reproductive Mode
The genus reproduces sexually by spawning in the wild and asexually through budding and fragmentation. Aquarium propagation depends on the asexual pathway, where a severed branch heals over and continues growing as a clone of the parent colony.
Fragging / Asexual Propagation
Propagation is done by cutting a branch from the colony. A clean cut from a diamond blade or coral saw heals faster and is less prone to infection than a crushed cut from blunt nippers. The branch is mounted and given time to seal at the wound before being placed in its permanent spot.
- Choose a vigorous branch away from the colony base.
- Make a single clean cut with a diamond blade or saw.
- Affix the frag to a plug or rock and let the cut heal.
- Apply an iodine-based dip to protect the fresh wound.
Conditions for Propagation
Recovery is best in stable water with medium to medium-high lighting and flow. Consistent alkalinity and clean conditions help the cut surface close and the branch re-establish polyps.
Common Challenges
As with the rest of the genus, the principal risk is aggression toward tankmates. Hydnophora extrudes mesenterial filaments loaded with digestive enzymes and can produce sweeper tentacles reaching several inches, killing back corals placed too close. A new grandis frag should be isolated with a generous buffer of open rock.