How to Frag SPS Corals: Cutting Acropora and Montipora Safely

Propagating your own small polyp stony corals is one of the most rewarding skills a reefer can develop. Knowing how to frag SPS corals lets you share colonies with fellow hobbyists, recover damaged pieces, and even generate a little income from your reef tank. At Gensou Aquascaping, 5 Everton Park, Singapore, we have fragged thousands of SPS pieces over the years and refined a workflow that keeps parent colonies healthy and maximises frag survival rates.

Essential Fragging Tools

A clean cut is everything. For branching Acropora, a pair of stainless steel bone cutters works best for branches up to 8 mm in diameter. Thicker stems call for a Dremel fitted with a diamond-coated cutting wheel. Montipora plating corals are easier to handle with a sharp razor blade or tile nippers, which produce less vibration and dust. You will also need coral glue (cyanoacrylate gel), frag plugs or discs, a small container of tank water, and clean towels. Budget around $40-60 SGD for a decent starter kit from local marine shops or Shopee.

Preparing the Parent Colony

Feed your colony well for at least a week before fragging. Target-feed amino acids or coral food such as Reef-Roids to boost energy reserves. On the day itself, turn off your return pump and wavemakers to prevent loose fragments from getting sucked into equipment. Some reefers dose a small amount of iodine to the tank beforehand to support tissue recovery, though this is optional.

Cutting Branching Acropora

Select a branch tip at least 2.5 cm long with visible polyp extension. Position your bone cutters roughly 1 cm below the growing tip and make one swift, decisive cut. Avoid crushing or twisting the skeleton. If the branch is thick, score the surface lightly with a Dremel first, then snap with cutters to keep the fracture clean. Place the frag immediately into a small cup of tank water to rinse off any mucus and skeletal debris. Work quickly; SPS tissue exposed to air for more than 30 seconds begins to stress.

Fragging Plating Montipora

Plating Montipora capricornis and similar species require a slightly different approach. Turn the colony upside down and identify a section along the outer growth edge. Use tile nippers to cut triangular or square pieces roughly 3 cm across. The growth edge heals fastest because it contains the most active tissue. Avoid cutting through the thickest central portion of the plate unless you are rescuing a dying colony, as this area has less regenerative tissue and the skeleton is dense.

Mounting Frags to Plugs

Dry the base of the frag lightly with a paper towel for two to three seconds, just enough for the glue to grip. Apply a generous blob of cyanoacrylate gel to the frag plug and press the cut end firmly into the glue. Hold for about ten seconds. If working with a flat Montipora piece, angle it slightly upward on the plug so light reaches both the top and the edges. Drop the mounted frag into your grow-out container or directly onto the frag rack in your display.

Post-Frag Care and Placement

Place new frags in a lower-light, moderate-flow area for the first week. Direct high-intensity lighting can bleach freshly cut tissue. After seven to ten days, you should see tissue beginning to encrust over the exposed skeleton. At that point, gradually move the frag higher on your rack. In Singapore’s warm climate, keep your tank temperature stable at 25-26 degrees Celsius during the recovery period. Even a brief spike to 29 degrees Celsius can stall healing and invite algae colonisation on the exposed skeleton.

Common Fragging Mistakes

Cutting frags too small is the most frequent error. Pieces under 1.5 cm have very little energy reserve and often brown out before they can recover. Another mistake is fragging a colony that is already stressed. If polyps have been retracted for days or the coral shows signs of tissue necrosis, fragging will only accelerate decline. Dirty tools spread pathogens between colonies as well, so dip your cutters in a dilute iodine solution between each cut.

Dipping and Quarantine

Every frag should be dipped in a coral pest treatment such as CoralRx or Bayer insecticide solution before placement. This removes hitchhikers like Acropora red bugs, flatworms, and nudibranchs that are difficult to spot on small pieces. Swirl the frag gently for five to ten minutes, then rinse in clean saltwater. If you maintain a dedicated frag tank, quarantine new frags there for two weeks before introducing them to your display reef. This extra step has saved countless colonies from pest outbreaks in our experience.

Related Reading

• How to Frag LPS Corals: Splitting Torch, Hammer and Frogspawn
• How to Aquascape a Mixed Reef: LPS and SPS Placement Strategy
• How to Aquascape an SPS-Dominant Reef: Acropora, Light and Flow
• How to Set Up a Coral Frag Grow-Out Tank: Layout for Propagation
• How to Set Up a Coral Frag Grow-Out Tank: Light, Flow and Racking