How to Coral Fragging for Saltwater Fish - Step by Step
Step-by-step guide to Coral Fragging for Saltwater Fish. Includes time estimates, tips, and common mistakes to avoid.
Coral fragging can fit naturally into a saltwater fish system when it is planned around fish behavior, nutrient load, and biosecurity. This step by step guide shows marine fish keepers how to safely cut, mount, and recover coral frags without stressing livestock or destabilizing the tank.
Prerequisites
- -A stable saltwater aquarium or frag system with salinity at 1.025-1.026 SG, temperature 76-79 F, alkalinity 8-9 dKH, calcium 400-450 ppm, and magnesium 1250-1400 ppm
- -Healthy donor coral with visible growth margins and no signs of tissue recession, brown jelly, flatworms, or red bugs
- -Coral cutters or bone cutters for branching corals, a diamond band saw or rotary tool for thick skeletons, and a sharp scalpel or coral scissors for soft corals
- -Powder-free nitrile gloves, protective eyewear, and good ventilation, especially when handling zoanthids or palythoas
- -Frag plugs, ceramic discs, or small rubble pieces plus thick cyanoacrylate gel and reef-safe epoxy
- -At least two clean containers of tank water, one for cutting and rinsing and one for dip and recovery
- -Coral dip appropriate for your coral type, such as an iodine-based dip or commercial pest dip, mixed according to label directions
- -A low to moderate flow grow-out area or frag rack placed away from aggressive fish like angelfish, butterflyfish, triggers, and known coral nippers
- -Basic knowledge of your lighting zones, including approximate PAR in the intended frag placement area
Select a donor colony that has been stable for at least 3-4 weeks, shows full polyp extension, and has no active disease or pest signs. In mixed fish systems, observe whether any tankmates nip at LPS flesh, soft coral polyps, or fresh glue mounts before you cut. If you keep coral-picking species, move the frags to a protected frag rack, breeder box, or separate frag tank for recovery.
Tips
- +Branching SPS such as birdsnest or montipora digitata are usually easier starter corals than fleshy LPS in fish-heavy tanks.
- +Skip fragging any colony that recently suffered a salinity swing, alkalinity drop, or fish aggression.
Common Mistakes
- -Fragging a stressed coral just because it has grown enough to cut.
- -Ignoring occasional nipping from fish that can become constant once fresh frags are added.
Pro Tips
- *Frag after your main fish feeding, not before, so active feeders are less likely to harass fresh mounts and your hands can work in calmer water.
- *If you run a mixed reef with angelfish or butterflyfish, recover frags in a separate frag tank or protected box for at least 7 days before placing them in the display.
- *For SPS grow-out, keep alkalinity swings under 0.3 dKH per day and avoid chasing pH with sudden dosing after fragging.
- *Use color-coded plugs or labeled racks to track which frags came from fast-growing, pest-free parent colonies worth propagating again.
- *When mounting to rubble for fish displays, choose flatter pieces that wedge securely into crevices so snails, hermits, and strong-flow areas cannot flip the frag.
Keep a clean backup log for test day.
The Printable Reef Logbook gives you water testing, dosing, maintenance, and livestock worksheets you can print or save as a PDF.