Marine & AlgaeAdvanced🌤️ Bright indirect

Maiden's hair / turtle weed

Chlorodesmis fastigiata · also called Maiden's hair, Maidens hair algae, Turtle weed, Chlorodesmis

⚠ Mildly toxic

Can cause mild irritation or GI upset if chewed.

Chlorodesmis grows as dense, vivid-green tufts of fine, soft, hair-like filaments, sold in the hobby as 'maiden's hair' (and known scientifically as turtle weed). It is a beautiful turf/display macro and a great microfauna refuge — BUT, unlike most macros, it is chemically defended and is NOT fully coral-safe: its tissue carries a toxic diterpene that can damage corals on contact.

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	Udoteaceae
Native origin	Indo-Pacific coral reefs
Care difficulty	Advanced
Light	Bright indirect
Pet toxicity	Mildly toxic

Light

Wants moderate-to-strong reef lighting (medium-high aquarium light / good PAR) for dense, vivid-green tufts; insufficient light thins and dulls it. Display reef LEDs work well. Mapped here to bright lighting needs.

Water

Standard reef parameters: temperature 24-27 C (75-80 F), salinity ~1.025 SG, pH 8.1-8.4, alkalinity 8-11 dKH. Uses nitrate and phosphate. Iron and trace elements support the bright green color. Prefers a stable, established system. No CO2 (marine).

Soil & potting

Attaches to rock and rubble with a holdfast, forming a low turf. In the aquarium it is attached to or wedged onto rockwork, ideally away from corals (see toxicity). Not buried; no aquasoil or root tabs — it feeds from the water column.

Environment — humidity, temperature, placement

Submersed only. No CO2 (marine). Moderate flow keeps the fine filaments clean. Best displayed on its own rock or in a refugium where it cannot touch corals; its dense tuft is excellent habitat for copepods and amphipods. Allelopathic to corals, so placement matters more than with a typical reef-safe macro.

Propagation

Spreads by vegetative growth of its filament tufts and by the holdfast creeping over rock; pull or cut a tuft with some holdfast and attach it elsewhere to propagate. In nature it is famously 'farmed' and defended by territorial damselfish, which weed competing algae out of their Chlorodesmis patches.

Toxicity detail

Listed as mild toxicity because it is chemically defended and NOT fully coral-safe: Chlorodesmis produces the toxic diterpene chlorodesmin to deter generalist grazers, and this compound can harm corals it contacts. It is not a hazard to fish, shrimp, or humans (a few specialist gobies even eat it to borrow its toxicity), but keep it away from corals. It is not a regulated/invasive species. Never release into 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

Chlorodesmis - Wikipedia (encyclopedia)
Maiden's Hair (Chlorodesmis) macroalgae - MosaicMacros (care guide)