The First Cut

Fragging — cutting a coral into pieces that each grow into new colonies — is the moment a coral keeper becomes a coral propagator. It sounds violent, and the first cut is nerve-wracking, but it rests on the biology from chapter one: because a coral is a colony of identical polyps connected by tissue, a clean-cut piece is a complete animal that will heal and grow. You are not wounding one organism; you are dividing a colony.

Done well, fragging is calm, quick, and clean. Done carelessly, it stresses or kills the coral and can hurt you. This chapter makes it a craft.

Why Frag At All

There are good reasons beyond curiosity. Fragging lets you control a coral that is outgrowing its space or overtaking neighbors. It lets you propagate a color you love, trade with other reefers, and eventually offset the endless tank tax by selling frags. It creates backups — a frag of a prized coral kept elsewhere survives if disaster strikes the mother colony. And it is simply satisfying, the point at which the hobby starts giving back what you put in. Scaling this up into a real collection is the subject of the frag-to-colony chapter; this chapter is about the cut itself.

The Operating Table

Approach fragging like minor surgery, because hygiene and preparation prevent most problems. Before you cut anything, set up a clean station: a bowl of tank water to hold cut frags, your tools, frag plugs or rubble to mount onto, glue, paper towels, and gloves. Work quickly so corals spend minimal time out of water, keep everything clean to avoid introducing infection to open tissue, and have your mounting materials ready before you cut so a fresh frag is not sitting around waiting.

A dedicated coral fragging kit — bone cutters, a scalpel or single-edged blade, cyanoacrylate gel, and ceramic frag plugs — puts everything you need in one place and, importantly, gives you tools clean and sharp enough to make quick clean cuts. Dull tools crush tissue; sharp tools sever it. That distinction matters more to coral survival than almost anything else in the process.

Safety: The Zoanthid Warning

Before any technique, a hard safety rule. Many zoanthids and Palythoa carry palytoxin, among the most lethal natural poisons known, and fragging is exactly when people get hurt — a splash in the eye, a cut on the hand, or fumes from scraping them out of water have sent aquarists to the hospital. When fragging zoas or palys: wear gloves and eye protection without exception, never do it dry or with heat, work in water or keep the coral wet, wash thoroughly afterward, and keep the area clear of open food and drinks. Take this seriously. It is the one part of coral keeping that can genuinely injure you.

Cut Lines by Coral Type

Different coral structures frag differently. Match the technique to the animal.

Soft Corals

Softies are the easiest. Most leathers, mushrooms, and similar corals are simply cut with a clean sharp blade or scissors — a slice of a leather cap, a mushroom cut through the mouth, a piece of a colony. The cut piece is then held or secured near the rock until it attaches on its own, since glue does not bond well to slippery soft tissue. Softies regenerate readily and the mother heals fast.

Zoanthids and Mats

Colonial polyps growing on a mat or rock are separated by cutting the mat between polyps, ideally taking a small chunk of the underlying rock or plug with each piece. Frag them off a plug rather than the display rock when possible. Gloves on, always.

LPS Corals

Branching LPS like frogspawn, hammer, and torch are fragged by cutting or snapping an individual head or branch off the colony with bone cutters, cutting through the skeleton well below the flesh so the polyp itself is not crushed. Encrusting LPS like acans are cut through the skeleton between polyps with a saw or cutters. Cut cleanly and quickly, keep the fleshy polyp intact, and give LPS frags extra healing time and gentle conditions.

SPS Corals

SPS are in some ways the simplest to frag: snip a branch off an Acropora or cut a piece of encrusting montipora with bone cutters. The skeleton is the coral, so a clean snip yields a frag with minimal fuss. SPS frags heal and encrust quickly given good conditions, which is why the hobby is flooded with SPS frags.

Mounting to Plugs

Once cut, a frag needs to be secured so it can heal in place. The standard method is cyanoacrylate gel — reef-safe super glue gel — used to bond the frag's skeleton or base to a ceramic frag plug or a piece of rubble. Dry the plug and the frag base briefly, apply the gel, press the frag on, and hold it a few seconds until it grabs, then return it to water. For soft corals that will not glue, secure the frag with a tiny rubber band, a toothpick, or by wedging it into a crevice until it attaches naturally over days. Larger or awkward frags can be set with two-part epoxy putty instead of or alongside the glue.

Aftercare: The First Two Weeks

A fresh frag is a wounded animal, and the first two weeks decide its fate. Many propagators give a new frag a brief, gentle bath in a coral dip before it goes on the rack, both to knock off any pests disturbed by the cut and to reduce the chance of infection at the open wound. Then place frags in a low-flow, moderate-light spot — a frag rack in the lower-middle of the tank is ideal — so they are not blasted while the cut heals. Keep water stable and clean, since open tissue is vulnerable to infection. Expect the frag to look unhappy at first: closed up, maybe slightly receded at the cut. Within days to a couple of weeks it should reopen, begin to heal over the cut edge, and start to encrust onto the plug. Resist moving or fiddling with it. The healing and grow-out phase gets its own full treatment in the next chapter.

Building Confidence With the First Cuts

The hardest part of fragging is psychological: the first cut into a coral you paid for feels like vandalism. Make it easier by starting where the stakes are low. Take your first cuts on a cheap, fast-growing, forgiving coral — a green star polyp mat, a bit of leather, a hardy zoa colony, or an encrusting montipora. These heal quickly and grow back readily, so a clumsy first attempt costs you almost nothing and teaches you the motions.

Once you have watched a few of your own frags close up, heal over, and encrust onto their plugs, the fear evaporates and fragging becomes routine. You will start to see your corals not as fragile ornaments but as renewable, dividing colonies — which is exactly what they are. That shift in perspective, from keeper to propagator, is the real graduation, and it happens the moment your first frag reopens on its plug and you realize you did not hurt it at all. You helped it multiply.

FAQ

How do I frag a coral for the first time?

Start with an easy soft coral or a hardy SPS like montipora. Set up a clean station with tank water, sharp tools, plugs, and glue ready before you cut. Make one quick clean cut through the skeleton or tissue, glue the frag's base to a plug, and place it in low flow and moderate light to heal. Work fast to minimize time out of water, and keep everything clean.

What tools do I need to frag corals?

At minimum: bone cutters for stony corals, a sharp scalpel or blade for soft corals and mats, reef-safe cyanoacrylate glue gel for mounting, and frag plugs or rubble to mount onto. A dedicated fragging kit bundles these with clean, sharp tools, which matters because sharp tools make quick clean cuts while dull ones crush tissue and stress the coral.

Is fragging corals dangerous?

The coral is rarely harmed by a clean cut, but zoanthids and Palythoa carry palytoxin, a genuinely lethal poison, and fragging is when people get exposed. Always wear gloves and eye protection when fragging zoas, never cut them dry or with heat, keep them wet, and wash up thoroughly afterward. For other corals the main risk is to the coral, minimized by clean sharp tools and fast, gentle handling.