Caulerpa serrulata
| Care Level | Easy |
| Lighting | Moderate |
| Water Flow | Low to moderate |
| Placement | Refugium preferred; display only with active control |
| Aggression | Peaceful, but invasive |
| Coloration | Bright to olive green |
Overview
A hardy, fast-growing true Caulerpa with flat, ribbon-like blades that twist along their length and carry finely serrated, saw-toothed edges — hence the name. It is an excellent nutrient exporter and a classic refugium alga, though in a display tank it needs managing, because like all Caulerpa it travels by runners and goes where it pleases.
Care & Placement
Very easy. Give it moderate light and gentle flow and it will take off on its own. Keep it confined to a refugium or an isolated island rock, since runners creep across the aquascape and will overgrow corals given the chance. Harvest it regularly rather than letting it mature unchecked.
Feeding
Photosynthetic and a strong consumer of nitrate and phosphate, which is exactly why it earns a place in a refugium. Remember the export only happens when you harvest and physically remove the growth — algae left to grow and die back returns those nutrients straight to the tank.
Propagation
Trivially easy. A cut runner or blade fragment will anchor and grow; most people end up giving it away rather than propagating it deliberately.
Cautions
The one that matters: Caulerpa can “go sexual” (sporulate), releasing its contents into the water, turning it milky and dying back all at once — which can crash water quality overnight. Reduce the risk by harvesting regularly so the algae never gets old and crowded, avoiding sudden lighting changes, and running refugium light on a reverse or 24-hour schedule. It is also genuinely invasive and will overgrow corals if left alone, and some regions restrict Caulerpa species outright, so check your local rules.