Discosoma sanctithomae (St. Thomas Mushroom) Propagation & Fragging Guide

How to propagate the Caribbean mushroom corallimorph Discosoma sanctithomae: asexual reproduction and fragging by cutting and reattaching cuttings, with low-flow healing conditions.

Overview

Discosoma sanctithomae is a Caribbean mushroom corallimorph, often called a mushroom anemone but biologically a corallimorpharian. Reef Builders notes that taxonomically this form has also been treated as Rhodactis osculifera, reflecting ongoing debate; regardless of placement, husbandry and propagation follow the same mushroom approach. Corallimorphs are essentially stony corals without a calcium carbonate skeleton and are hardy, beginner-friendly reef invertebrates.

Reproductive Mode

Like other mushroom corallimorphs, D. sanctithomae reproduces mainly asexually in the hobby. Reef Builders documents asexual reproduction via pedal laceration in Discosoma and notes that established Discosoma spread and multiply quickly. Sexual reproduction is broadcast and pelagic and is not part of normal hobby propagation.

Asexual Propagation / Fragging

Hobbyists frag mushrooms by deliberate cutting. Reef Builders reports that Discosoma heal well from cutting and grow quickly afterward, which makes them an ideal first propagation attempt. The hardest part is reattaching the cuttings, because neither rubber bands nor glue hold the soft tissue directly.

The workable method is to set each cutting onto a small piece of substrate and glue that substrate to a larger rock in the aquarium; the mushroom attaches itself as it heals. Pieces shed naturally through pedal laceration also drift, settle and regrow into new polyps without intervention.

Conditions for Propagation

Reef Builders recommends lower light (around 100 PAR or less) and minimal flow, observing that the best polyp extension is reached in near-stagnant water. Low flow additionally lets dislodged polyps settle and re-anchor, raising the success rate of fragging cuttings.

Sexual Reproduction

Sexual reproduction occurs by broadcast spawning into open water with pelagic larvae, a process not reproduced in closed aquaria. In practice, propagation of D. sanctithomae in the hobby is entirely asexual.