Blastomussa merleti Propagation Guide

How to propagate Blastomussa merleti, the small-polyp mini blasto: dividing its dense colonial heads on the branching skeleton while protecting its sensitive flesh.

Overview

Blastomussa merleti is a large-polyp stony coral in the genus Blastomussa with smaller polyps than B. wellsi, forming dense colonial growth. Each polyp sits on its own corallite, and the heads are joined by a shared tissue base into a tight colony. This colonial structure of separate polyps on connected stalks allows the coral to be divided between heads.

Reproductive Mode

Hobbyists propagate Blastomussa merleti asexually by fragmentation. Because the colony is made of many small polyp heads on individual corallites linked by tissue, it can be cut between polyps into smaller groups or single heads, each of which grows into a new colony. The species is adaptable but a slow grower.

Fragging / Asexual Propagation

1. Keep the colony fully submerged while it is handled so the small polyps stay protected through the cut.
2. Read the branching pattern; plan cuts so each frag retains one or more polyps on their own skeleton.
3. Cut between polyps, going as far below each head as possible to avoid nicking the polyp tissue.
4. Use a rotary tool or band saw, as the dense skeleton is hard to split cleanly with bone shears.
5. Mount each frag on a plug and keep it in low flow and modest light until it recovers.

Cutting parallel to the polyp surface lets a dense merleti colony break apart into fun-sized single-head frags.

Conditions for Propagation

Merleti is fairly adaptable to different conditions, with low to moderate lighting being fine; it does not like strong SPS flow. Stable temperature around 24-26 degrees Celsius, pH 8.1-8.4, and consistent alkalinity, calcium, and magnesium help frags heal and resume growth.

Common Challenges

Like its relatives, Blastomussa merleti has extremely sensitive flesh that is susceptible to infection if it is damaged, so careless cuts can lead to tissue loss. The coral grows slowly, but regular feeding keeps frags consistent and a little faster to fill in.