Neurymenia · also called Red Sawblade, Corkscrew Saw, Red Sword
Neurymenia is a red macroalgae with long, narrow, saw-edged blades in reddish-brown tones. N. fraxinifolia is a widespread Indo-Pacific species. Kept forms such as Red Sawblade are often misidentified as Cryptonemia crenulata, which has frilly blades. Keepers have little experience with its care.
Educational only. Some KinStation entries are reviewed by licensed veterinarians, but none can 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
Rhodomelaceae
Native origin
Indo-Pacific, from East Africa to New Caledonia and Fiji
Care difficulty
Intermediate
Light
Medium light
Pet toxicity
Toxicity unknown
Light
Keepers have little experience with its light needs, so start with moderate reef lighting and change it gradually. Watch the reddish-brown color: fading or sudden bleaching suggests the light is too strong or has changed too quickly. Hold steady once the blades look healthy.
Water
Standard reef parameters: 23-27 C (74-80 F), salinity ~1.025 SG, pH 8.1-8.4. No specific needs are recorded. Keep salinity and temperature steady, and keep nitrate and phosphate measurable rather than stripped out. As with other rarely kept red algae, slow changes and regular testing are the safest approach.
Soil & potting
Treat it as an attached alga that grows on hard surfaces rather than in sand. Keepers have little recorded detail, so anchor a blade base against rock or rubble with line and leave it undisturbed. Avoid burying the base, and check the tie does not cut into the tissue.
Environment — humidity, temperature, placement
It is widespread across the tropical Indo-Pacific from East Africa to New Caledonia and Fiji, so warm reef conditions at 23-27 C (74-80 F) are a fair match. Steady moderate flow in a display or macroalgae tank is a cautious start. Give long blades room to move without snagging.
Propagation
Keepers have little record of propagating it. The likely route is trimming a healthy blade section and tying it to rubble, though it is unclear how well cuttings attach. Corkscrew Saw and Red Sword are hobby names for forms with twisted or sword-shaped blades, not confirmed species.
Toxicity detail
No toxicity data for tank animals was found, so the rating stays unknown. No grazing deterrent or coral smothering risk is recorded for this genus. Its family includes chemically defended algae, so do not assume it is harmless, and keep blades from resting on corals.
Varieties & cultivars
Natural forms are the wild species; cultivars are selectively-bred colour or variegation forms of the same plant.
Natural forms3
Red Sawblade
Neurymenia fraxinifolia. A red alga with long, serrated blades in a reddish-brown tone. It is often misidentified as Cryptonemia crenulata.
Little is recorded about its care, so keep conditions stable and change lighting gradually.
Corkscrew Saw
Neurymenia sp. A red alga with long, serrated, reddish-brown blades, and the name suggests they twist like a corkscrew. It is often misidentified as Cryptonemia crenulata.
Little is recorded about its care, so keep conditions stable and change lighting gradually.
Red Sword
Neurymenia sp. A red alga with long, serrated, reddish-brown blades shaped like swords. It is often misidentified as Cryptonemia crenulata.
Little is recorded about its care, so keep conditions stable and change lighting gradually.
KinStation
Medium light
Little is recorded about its care, so keep conditions stable and change lighting gradually.