How to Frag Corals: Tools, Glue & Healing

Fragging is the reef keeper skill that turns one healthy coral into many. Whether you are expanding your own collection, building trading inventory for local reef club swaps, or creating backup copies of irreplaceable specimens, understanding how to cut, mount, and heal coral frags opens an entirely new dimension of the hobby.

Essential Fragging Tools

The basic fragging toolkit is straightforward: a sharp pair of coral bone cutters for branching stony corals, sharp scissors or a razor blade for soft corals, cyanoacrylate gel (super glue gel), two-part marine epoxy for larger pieces, ceramic frag plugs, and a container of clean saltwater for rinsing. A Dremel rotary tool with a diamond cutting wheel handles larger LPS fragging jobs that require cutting through dense skeleton. Protective gloves and eye protection are essential, especially when working with zoanthids that contain palytoxin.

Work in a clean, well-lit area with a towel-covered surface. Keep a container of tank water nearby for keeping frags wet during the mounting process — coral tissue dries quickly in air and even brief air exposure damages delicate polyps. Have all tools and supplies ready before making the first cut so the process moves quickly and the coral spends minimal time out of water.

Fragging Soft Corals

Soft corals are the easiest to frag because they lack rigid skeletons. Mushroom corals often split naturally — you can encourage splitting by cutting a mushroom in half with a razor blade. Each half regenerates into a complete mushroom within two to four weeks. Leather corals are cut with sharp scissors; a clean cut through the stalk produces a frag that can be rubber-banded to a frag plug until it attaches naturally.

Zoanthid colonies are separated by slicing through the connective mat between polyps with a sharp blade. Work carefully and slowly — zoanthids produce palytoxin, and cutting releases it. Wear gloves and eye protection, work in a ventilated area, and never put your face close to the work surface. After cutting, place the frag in clean saltwater and observe for polyp extension over the following days.

Fragging LPS Corals

LPS fragging requires cutting through calcium carbonate skeleton without crushing the surrounding tissue. Euphyllia species — torch, hammer, frogspawn — are fragged by cutting at natural branch points where individual heads connect to the main skeleton. Use bone cutters for clean cuts at branch junctions. A Dremel with a diamond wheel provides cleaner cuts on dense, thick skeleton areas that bone cutters would crush rather than cut.

Brain corals and plate corals can be sectioned but have slower recovery times than branching LPS. Use a band saw or Dremel to make clean, straight cuts through the skeleton. Each section needs enough tissue to sustain itself — cutting too small produces frags that lack sufficient photosynthetic tissue to survive independently.

Fragging SPS Corals

SPS fragging is the most straightforward technique despite SPS being the most demanding corals to keep. Acropora and other branching SPS species snap cleanly at branch junctions — simply grip the branch with bone cutters or your fingers and snap at the junction. The clean break produces a frag with an exposed skeleton base that attaches readily to a ceramic plug with super glue gel.

Encrusting SPS species like Montipora can be chipped off the rock with a flat chisel or frag tool, producing a flat piece that is glued to a frag disc or small piece of rubble rock. The key is getting enough base tissue for the frag to encrust outward from — a thin sliver with minimal tissue often bleaches and dies before establishing.

Mounting and Healing

Apply a small dot of cyanoacrylate gel to a dry frag plug, press the coral base onto the glue, and hold for ten to fifteen seconds until the bond sets. The glue cures instantly on contact with water — submerge the mounted frag immediately after the initial bond to prevent the exposed tissue from drying. For larger or irregularly shaped frags, two-part marine epoxy provides a moldable adhesive that fills gaps between the frag and the plug surface.

Place freshly mounted frags in a low-flow, moderate-light area for the healing period. Strong flow can dislodge fresh glue bonds, and intense light stresses tissue that is already recovering from the cut. As the frag shows signs of recovery — polyp extension for soft corals and LPS, tissue encrusting over exposed skeleton for SPS — gradually move it to a position with appropriate light and flow for its species.

Healing timelines vary by coral type. Soft corals heal fastest — mushrooms and leathers begin extending tissue within days. LPS corals typically show full polyp extension within one to two weeks if the cut was clean and the frag is healthy. SPS corals take the longest — tissue encrusting over the cut surface and the frag plug usually takes two to six weeks, with some species taking longer in suboptimal conditions.

Common Fragging Mistakes

The most common fragging mistake is cutting too small. A frag needs enough tissue and skeleton to sustain itself metabolically — a tiny sliver of coral with minimal photosynthetic tissue often lacks the energy reserves to heal the cut wound and establish on a new plug simultaneously. For SPS, frag pieces should be at least one inch long. For LPS, each frag should include at least one complete head or a section large enough to sustain independent polyp function. For soft corals, the piece should be substantial enough that the cut surface is a small proportion of the total tissue area.

Using dull tools creates crushed edges that heal slowly and are prone to infection. Bone cutters should be sharp enough to make clean cuts through skeleton without crumbling the surrounding structure. Replace or sharpen cutting tools regularly — a dull Dremel diamond wheel generates heat from friction that can cook tissue adjacent to the cut line, causing additional damage beyond the cut itself.

Fragging stressed or recently acquired corals is another frequent error. A coral that is still acclimating to your tank, recovering from shipping stress, or showing signs of poor health should be left alone until it demonstrates active growth and full polyp extension for at least two to three months. Fragging adds significant physical stress — imposing that stress on a coral already under metabolic pressure compounds the damage and frequently results in the death of both the frag and the parent colony.