Marine & AlgaeIntermediate🌗 Medium light
Caulerpa
Caulerpa prolifera · also called Caulerpa, Feather caulerpa, Grape caulerpa (other spp.), Sea grapes (loosely)
Can cause mild irritation or GI upset if chewed.
Caulerpa is a fast-growing nutrient-export macroalgae with attractive flat blade-like fronds, popular in refugiums and macro display tanks. It is effective but riskier than chaeto because it can "go sexual" and release reproductive cells that crash water quality. It is also a regulated/invasive genus in many jurisdictions.
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Quick facts
| Category | Marine & Algae |
| Family | Caulerpaceae |
| Native origin | Tropical and subtropical Atlantic (including Caribbean/Gulf of Mexico) and Mediterranean; warm coastal waters worldwide |
| Care difficulty | Intermediate |
| Light | Medium light |
| Pet toxicity | Mildly toxic |
Light
Medium aquarium lighting; full-spectrum refugium LEDs or display reef lighting both work. A consistent long photoperiod (often run 24/7 in refugiums) is commonly used to discourage it from entering its sexual (sporulation) phase, though stable nutrients and undisturbed growth matter more. Higher light boosts growth and nutrient uptake.
Water
Reef parameters: 22-27 C (72-80 F), salinity ~1.025 SG, pH 8.1-8.4, alkalinity 8-11 dKH. Consumes nitrate and phosphate readily. Sensitive to abrupt parameter swings and harsh pruning, which can trigger a crash. Iron and trace elements support vigorous growth. No CO2 (marine).
Soil & potting
Anchors with creeping horizontal stolons and root-like rhizoids. In a display it can be allowed to grip rock or sand; in a refugium it forms a mat. It is NOT buried - the stolon runs along the surface and sends up upright fronds.
Environment — humidity, temperature, placement
Submersed only. CO2 not required. Best in a refugium with moderate flow, or in a dedicated macroalgae display. Many keepers run lighting continuously (no dark period) to reduce the chance of going sexual. Prune conservatively and never let large amounts die at once.
Propagation
Spreads aggressively by runners (stolons); any fragment with a node can regenerate, so trimming and replanting pieces is the standard method. Can also reproduce sexually by releasing gametes - this turns the algae white/clear and is a sign of an imminent crash; harvest before it gets too large. This same regenerative vigor is why it is a notorious invasive.
Toxicity detail
Produces caulerpin/caulerpenyne secondary metabolites that deter most grazers and can be mildly irritating; generally safe to fish and corals in the tank but should not be fed to herbivores in quantity. IMPORTANT: the aquarium (Mediterranean) strain of 'Caulerpa taxifolia' is a U.S. federal noxious weed, and California bans the sale/possession/transport of C. taxifolia plus several look-alike Caulerpa species (including C. prolifera and others). The genus is also tightly regulated in Australia, New Zealand, and the EU. Never release any Caulerpa to the wild; check local law before keeping or shipping.
Growth stages
How this plant changes through its life — each stage often has its own care, diet and space needs.
Sources
- Caulerpa - Wikipedia (encyclopedia)
- Caulerpa taxifolia - Federal Noxious Weed List, USDA APHIS (regulatory)
- Prohibited Caulerpa species - California Code of Regulations / CDFA (regulatory)
- Caulerpa Macroalgae in the Reef Refugium - Reef2Reef (care guide)