Symphyllia valenciennesii Propagation Guide

How to propagate the massive closed-brain coral Symphyllia valenciennesii (Lobophylliidae) by cutting the colony skeleton, plus notes on its broadcast spawning in the wild.

Overview

Symphyllia valenciennesii is a massive, colonial closed-brain coral in the family Lobophylliidae. Like other meandroid brain corals, it builds a single stony skeleton across which many polyps share continuous tissue and valley structures. Because the colony is one connected mass rather than a cluster of separable heads, propagation in aquaria relies on physically dividing the skeleton, while in the wild the species also reproduces sexually.

Reproductive Mode

The colony grows by adding new polyps and extending its valleys over the skeleton, a form of asexual budding that enlarges a single genetic individual. Brain corals of this group are also sexual reproducers that release gametes into the water column for external fertilisation. Both routes are relevant: the asexual route is what hobbyists exploit when fragging, and the sexual route is how new genotypes arise on the reef.

Fragging / Asexual Propagation

1. Choose a healthy, fully extended colony and cut along a low valley wall so each piece retains intact polyps and corallites.
2. Divide the stony skeleton with a band saw or a rotary cutting tool; massive brain skeletons are too thick for simple bone cutters.
3. Rinse fragments in clean saltwater to clear skeletal dust, then mount each piece skeleton-down on a plug or rock.
4. Place fragments in low-to-moderate flow and shaded light during recovery; tissue heals back over the cut edge across several weeks.

Conditions for Propagation

• Stable alkalinity, calcium and magnesium so the cut skeleton can re-calcify.
• Gentle flow over fresh cuts to remove debris without tearing recovering tissue.
• Reduced light immediately after cutting, returning to normal as the edge seals.
• Low dissolved nutrients and good water quality to limit algae on exposed skeleton.

Sexual Reproduction

On the reef, brain corals of this group spawn by releasing eggs and sperm into the water, where fertilisation and larval development occur externally before larvae settle and found new colonies. Captive spawning of large brain corals is uncommon and is not a practical home-propagation method.

Common Challenges

Cutting a massive skeleton is stressful: exposed edges can be invaded by algae or develop tissue recession if flow and water quality are poor. Recovery is slow, and a botched cut that crushes polyps rather than slicing cleanly reduces survival. Work quickly, keep cuts clean, and minimise air exposure.