Marine & AlgaeIntermediate🌗 Medium light
Grape caulerpa (sea grapes)
Caulerpa racemosa · also called Sea grapes, Grape caulerpa, Green caviar, Caulerpa racemosa
Can cause mild irritation or GI upset if chewed.
Caulerpa racemosa is the grape-bunch Caulerpa, with rounded vesicles ('grapes') borne on creeping stolons. Like the feather Caulerpa (C. prolifera) it is a fast nutrient-export macro and an edible green ('sea grapes' / 'green caviar'), but it shares the genus's two big risks: it can 'go sexual' and crash a tank, and the genus is regulated/invasive in many places.
Educational only. KinStation content is reviewed by licensed veterinarians but cannot replace an in-person exam. Always consult a licensed veterinarian or board-certified specialist for diagnosis, treatment, or any decision affecting your pet's health.
Quick facts
| Category | Marine & Algae |
| Family | Caulerpaceae |
| Native origin | Shallow temperate and tropical seas worldwide — including the Caribbean, Bermuda, and the western Atlantic from Florida to Brazil |
| Care difficulty | Intermediate |
| Light | Medium light |
| Pet toxicity | Mildly toxic |
Light
Medium reef/refugium lighting. A consistent, long photoperiod (refugiums are often run nearly 24/7) is commonly used to discourage it from entering its sexual (sporulation) phase, though stable nutrients and undisturbed growth matter more. Brighter light boosts growth and nutrient uptake.
Water
Standard reef parameters: temperature 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 to 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 grip rock or sand; in a refugium it forms a mat. It is NOT buried — the stolon runs along the surface and sends up the grape-bearing uprights.
Environment — humidity, temperature, placement
Submersed only. No CO2 (marine). Best in a refugium with moderate flow or a dedicated macroalgae display. Many keepers run lighting continuously (no dark period) to reduce the chance of going sexual. Prune conservatively, harvest before clumps get large, and never let a big mass 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 pale/clear and signals an imminent crash, so harvest before it gets too large. This same regenerative vigor is why Caulerpa 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 but should not be fed to herbivores in quantity. INVASIVE/REGULATED: a large variety (C. racemosa var. cylindracea) has invaded the Mediterranean and spread even more widely than the infamous C. taxifolia. The Caulerpa genus is restricted in California, Australia, New Zealand, and the EU. Check local law before keeping or shipping any Caulerpa, and never release it to the wild.
Growth stages
How this plant changes through its life — each stage often has its own care, diet and space needs.
Reviewed and signed off by: KinStation Editorial — pre-launch draft (pending horticulture review) on 2026-06-10
Sources
- Caulerpa racemosa - Wikipedia (encyclopedia)
- Prohibited Caulerpa species - California Code of Regulations / CDFA (regulatory)
- Grape Caulerpa (Caulerpa racemosa) - MosaicMacros (care guide)