Caulerpa taxifolia: Killer Algae — Propagation and Legal Warning

Caulerpa taxifolia, the infamous killer algae, propagates by stolon fragmentation. Read the heavy invasive and legal warnings before keeping this banned macroalga.

Overview

Caulerpa taxifolia is a light-green marine macroalga with stolons on the sea floor from which sparsely branched, feather-like upright fronds of roughly 20-60 cm arise. Despite its plant-like look, it consists of a single cell with many nuclei and has been identified as the largest known single-celled organism. It produces a defensive compound, caulerpenyne. An aquarium strain, a cold-resistant clone, was developed and distributed to public aquariums.

Propagation Method

Where legal, it propagates purely by fragmentation of the stolon. The aquarium strain shows reduced sexual reproduction, but fragments as small as 1 cm are capable of producing viable plants, which is exactly why it spreads so destructively. Division of the runner, not substrate cuttings, is the mechanism. This same trait is the core invasion hazard.

Step-by-Step

First confirm the species is legal to keep in your jurisdiction; if in doubt, do not propagate.
Work over a container so no fragment escapes; treat every cut piece as a potential invader.
With clean scissors divide the stolon into segments, each with a frond and rhizoids.
Anchor segments against rock so the rhizoids grip; keep flow gentle at first.
Bag and bin any offcuts; disinfect tools and never rinse them into a drain.

Conditions for Healthy Growth

It tolerates a wide range, roughly 18-28 °C, pH about 8.0-8.4, and moderate light, and is an aggressive grower — that cold tolerance is what let the strain colonise temperate seas. Sediment-rich sand suits the rhizoids, which take up nutrients from the substrate.

Maintenance

Harvest frequently to export nutrients and control the aggressive spread. Capture every offcut; never let trimmings drift to an overflow or sump outlet. All removed material goes into a sealed bag and then the trash.