Marine & AlgaeIntermediate🌗 Medium light

Dragon's breath algae

Halymenia sp. · also called Dragon's breath, Dragons breath macroalgae, Red dragon's breath, Halymenia

🐾 Pet-safe

Generally non-toxic to cats and dogs.

Halymenia, sold as "Dragon's Breath," is a striking fiery red, branching, flame-like macroalgae popular as a centerpiece in macro display tanks. It is one of the more decorative red macros but appreciates good light and stable conditions to keep its vivid color.

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	Halymeniaceae
Native origin	Tropical and subtropical reefs of the Indo-Pacific and warm coastal seas
Care difficulty	Intermediate
Light	Medium light
Pet toxicity	Pet-safe

Light

Medium reef lighting brings out the best red/orange color; as a red alga it does well under full-spectrum or blue-leaning LEDs and does not require extreme PAR. Too little light dulls it; very intense light can bleach it - aim for moderate, consistent lighting.

Water

Reef parameters: 23-27 C (74-80 F), salinity ~1.025 SG, pH 8.1-8.4, alkalinity 8-11 dKH. Uses nitrate and phosphate. Iron and trace-element dosing supports its intense coloration. Prefers stable, established water. No CO2 (marine).

Soil & potting

Not rooted into substrate; it attaches with a small holdfast. In the aquarium it is usually wedged into or attached to rockwork as a display piece, or allowed to tumble. No root tabs or aquasoil needed.

Environment — humidity, temperature, placement

Submersed only. No CO2. Moderate flow keeps detritus off its branches and helps coloration; avoid dead spots. Showcased in the midground/foreground of macroalgae display tanks. Reef-safe alongside corals and fish.

Propagation

Propagated by cutting off a branch and attaching it to new rock; fragments grow into new clusters. Spreads by branching growth. Slower and a bit more finicky to frag than chaeto or Gracilaria.

Toxicity detail

Reef-safe and non-toxic to fish, corals, and shrimp. Often left alone by many herbivores, helping it persist as a display plant. Not invasive or regulated in the aquarium hobby.

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.

Sources

Halymenia - Wikipedia (encyclopedia)
Dragon's Breath (Halymenia) Macroalgae Care - Reef2Reef (care guide)