Goniastrea retiformis (Honeycomb Brain) Propagation Guide

Propagating the honeycomb brain coral Goniastrea retiformis (Merulinidae) by cutting the massive colony skeleton, with notes on its reef spawning.

Overview

Goniastrea retiformis is a brain coral of the family Merulinidae that forms massive colonies, usually spherical or elongate, with a honeycomb arrangement of corallites and well-developed paliform lobes. Its polyps are typically visible only at night. Being a single connected colony, it is propagated by dividing the skeleton.

Reproductive Mode

The colony enlarges through asexual budding of polyps across the honeycomb skeleton, growing one genotype. Reef-building corals of this group also reproduce sexually by releasing gametes for external fertilisation. For aquarium propagation, only the asexual division of the colony is used.

Fragging / Asexual Propagation

Select a healthy colony and plan a cut between corallite rows.
Part the massive skeleton with a band saw so each frag keeps whole corallites.
Rinse skeletal dust and mount each frag cut-side down on a plug or rock.
Recover in moderate flow under reduced light while the edge tissues over.

Conditions for Propagation

Stable carbonate chemistry for skeletal regrowth.
Clean, moderate flow over the cut.
Reduced light in the first recovery weeks.
Low nutrients to keep exposed skeleton clear of algae.

Sexual Reproduction

On the reef, brain corals of this family take part in synchronised spawning, broadcasting gametes into the water for external fertilisation, followed by larval settlement. This is not a routine method for home propagation.

Common Challenges

Honeycomb brains are generally hardy, but exposed skeleton after a cut can be colonised by algae or recede if water quality slips. A clean saw cut and stable parameters support a faster heal.