Sea Grapes care guide
Sea Grapes (Caulerpa racemosa) — medium light, 22-28 °C, pH 8-8.4, no CO2.
Compiled by Aquairi from published sources · Published · Updated
Overview
Sea Grapes (Caulerpa racemosa) is an aquatic plant of the family Caulerpaceae, listed in the Aquairi knowledge base as a beginner-level species. It is typically grown under medium light and without obligatory CO2 injection on fine sand. Saltwater macroalgae forming branches with grape-like vesicles. Decorative in display refugiums; rapid grower that should be harvested often. Considered invasive in the Mediterranean.
Taxonomy
- Family: Caulerpaceae
- Genus: Caulerpa
- Scientific name: Caulerpa racemosa
- Common synonyms: Green Caviar
Habitat
Caulerpa is a genus of green marine macroalgae (Caulerpaceae) of warm seas worldwide; the entire alga is a single giant cell, with a creeping stolon, holdfast rhizoids and upright fronds. In the Aquairi knowledge base, populations associated with this form are recorded from Cosmopolitan.
Growth requirements
- Lighting: medium
- CO2: not required
- Temperature: 22-28 °C (72-82 °F)
- pH: 8-8.4
- GH: 8-12 °dGH
- Substrate: sand
- Maximum height: 15 cm
- Growth rate: fast
- Recommended placement: midground
Placement
Grown in a refugium or display, anchored among live rock; bright light and stable salinity drive growth and nutrient export from the system. In the Aquairi knowledge base this form is recommended for the midground under medium light and without obligatory CO2 injection, using fine sand.
Propagation
Spreads vegetatively along the stolon and from fragments; trimming runners and removing detached pieces controls its spread. Documented propagation techniques for this entry include: horizontal runners.
Common issues
Under stress or long darkness it can undergo a sudden reproductive event (going sexual), releasing gametes and crashing while clouding the water; regular harvest and a reverse-daylight refugium reduce the risk.
Caulerpa racemosa (Sea Grapes) Propagation by Stolon Division
Overview
Caulerpa racemosa, the sea grapes or green caviar, is a green marine macroalga. Many spherical or ovate side-shoots branch off its stolons and give the seaweed its name; horizontal stolons (runners) are anchored by rhizoids and the plant can reach about 30 cm tall. Like other Caulerpa, each plant is a single enormous cell with a large number of nuclei. It lives in shallow tropical and temperate seas, including the Caribbean, Bermuda and the American seaboard from Florida to Brazil.
In the aquarium it is a decorative, rapid-growing macroalga for display refugiums, valued for nutrient export. Because it spreads by runner, propagation means dividing the stolon, not taking substrate cuttings.
Propagation Method
Sea grapes propagate by fragmentation of the stolon. Small pieces of tissue only a few millimetres across are capable of growing into new plants, so dividing a runner that carries grape-like beads and rhizoids reliably yields new colonies. No rooting agents or special media are needed.
- Pick a firm, deep-green stolon section densely set with grape-like vesicles.
- Divide into segments, each retaining beads and some rhizoids.
- Anchor segments so rhizoids contact rock or sand.
Step-by-Step
- Choose a healthy clump with plump, green vesicles and no pale or translucent runner.
- With clean scissors cut the stolon between clusters into segments a few centimetres long, each with beads and rhizoids.
- Wedge each segment against live rock or set it on the sand so the rhizoids can grip.
- Keep flow gentle initially so segments anchor before drifting loose.
- Confirm establishment when new beaded shoots extend from the stolon.
Conditions for Healthy Growth
Maintain stable saltwater near 22-28 °C, pH about 8.0-8.4, and moderate light. As a fast grower it pulls down nitrate and phosphate. Sediment-rich sand helps because the rhizoids draw nutrients directly from the substrate, unlike macroalgae that feed only from the water column.
Maintenance
Harvest often: this is a rapid grower that should be cropped regularly to physically export nutrients and keep the clump open. Pinch or cut surplus runner and remove it from the system. Dispose of trimmings in the trash, never into a drain or natural water.