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Marine & AlgaeIntermediate🌗 Medium light

Red grape algae

Botryocladia occidentalis · also called Red grape, Red grape caulerpa (misnomer — not a Caulerpa), Sea grapes (red), Botryocladia

🐾 Pet-safe

Generally non-toxic to cats and dogs.

Botryocladia is a striking red macroalgae that grows as clusters of hollow, fluid-filled, grape-like vesicles on short branches, giving it the trade name "red grape." It is a decorative display macro for refugiums and macro tanks. Despite the nickname "red grape caulerpa" it is NOT a Caulerpa (it is a red alga, Rhodophyta) and so is not subject to the Caulerpa sale bans — it can legally ship to states like California.

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

CategoryMarine & Algae
FamilyRhodymeniaceae
Native originTropical and subtropical western Atlantic — Caribbean, Gulf of Mexico, and the Brazilian coast
Care difficultyIntermediate
LightMedium light
Pet toxicityPet-safe

Light

Medium reef/refugium lighting suits it. As a red alga (Rhodophyta) it colors up well under full-spectrum or slightly blue-shifted LEDs and does not demand extreme PAR; moderate, consistent light keeps the vesicles a deep wine-red. Too little light dulls it, while very intense light can bleach the bubbles.

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, so it contributes to nutrient export. Iron and trace elements support color and growth. Stable, established water is best. No CO2 (marine).

Soil & potting

Not rooted into substrate; it attaches with a small holdfast. In the aquarium it is wedged into or attached to rockwork as a display piece, or allowed to grow among other macros. No aquasoil or root tabs — it feeds from the water column.

Environment — humidity, temperature, placement

Submersed only. No CO2 (marine). Moderate flow keeps detritus off the vesicles and helps coloration; avoid dead spots where it can collect debris. Showcased in the midground/foreground of macroalgae display tanks and refugiums. Reef-safe alongside corals and fish.

Propagation

Propagated by cutting off a branched section of vesicles and attaching it to new rock; fragments grow into new clusters. Slower and a bit more delicate to frag than chaeto or Gracilaria — handle the bubbles gently, as popped vesicles can rot.

Toxicity detail

Reef-safe and non-toxic to fish, corals, and shrimp. Most herbivores leave it alone, helping it persist as a display plant. NOT a regulated/invasive species: because it is a true red alga and not a Caulerpa, it is not covered by the federal/California Caulerpa restrictions and ships legally nationwide. As always, never release any aquarium alga to the wild.

Growth stages

How this plant changes through its life — each stage often has its own care, diet and space needs.

Photo coming soon
Spore / recruit

Aquatic plants and macroalgae establish from spores, seeds, or drifting fragments that settle and attach to substrate or rock. Many freshwater aquarium plants and marine macroalgae also spread readily from a detached piece that takes root or holdfast.

Photo coming soon
Young growth

Young growth puts out its first blades, fronds, or leaves and anchors with roots or a holdfast. Submersed plants may look different from their emersed form, and growth speeds up as the plant adapts to the water's light and nutrients.

Photo coming soon
Mature

A mature aquatic plant or macroalga reaches its full size and characteristic shape, forming the dense growth, runners, or fronds typical of the species. Established plants spread to fill space and can be divided or trimmed to propagate.

Reviewed and signed off by: KinStation Editorial — pre-launch draft (pending horticulture review) on 2026-06-10

Sources

  1. Botryocladia occidentalis - World Register of Marine Species (WoRMS) (encyclopedia)
  2. Red Grape (Botryocladia) - MosaicMacros (care guide)
  3. Botryocladia (Red Grape) Macroalgae - ReefCleaners (care guide)