Udotea spp. — Mermaid’s Fan
The reef’s most elegant hand fan.
What You Get
Mermaid’s Fan is a calcareous macroalga with a broad, sculpted frond that naturally resembles a hand fan or Mermaid Tail. Found on sandy reef flats, seagrass beds, and hard-bottom areas throughout the Caribbean, these plants anchor themselves with a thick rhizoid base that extends deep into the substrate. In the ocean, fans may grow up to 12 inches, especially in bright, shallow habitats with stable chemistry.
We collect multiple species of Udotea, all sharing this iconic fan shape. In established aquariums with good calcium and a deep sand bed, they may produce new “daughter fans” near the base, slowly forming a small, living grove over time.
Why It Is Algaesome
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Striking, sculptural form: Its perfectly fanned frond creates an instant focal point in displays, lagoons, and macro gardens.
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Natural sand-bed specialist: Thrives when rooted in a 3-inch or deeper substrate, just like in the wild.
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Self-propagating beauty: Healthy plants may sprout new fans from the rhizoid base, gradually forming a small colony.
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Reef ready: Prefers strong calcium and alkalinity, making it a natural companion for reef aquariums.
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Left untouched: Not palatable to most herbivorous fish or invertebrates, so it typically remains intact.
Sizing & Availability
You will receive a single, rooted Mermaid’s Fan specimen, typically 3 inches tall. Frond shape, scalloping, and rigidity vary between Udotea species. Some fans appear smooth and rounded, while others show gentle lobes or slight texturing.
Traits
Color Light to deep green
Ease Easy with deep sand bed
Classification Calcareous green macroalgae
Nutrient Uptake Fair
Availability Regular, tide-dependent
Use Display macro; deep sand beds
Lighting Moderate to high
Flow Moderate
A Note from the Collectors:
Every macroalga we offer is hand collected, acclimated, and observed by our team before shipping. While we carefully try to remove other algae, sponges, and tiny hitchhikers, it is possible that a few goodies from the reef may tag along. It is a natural part of receiving genuine wild collected specimens.
Many species may arrive paler or whitish in color. This is completely normal. Macroalgae shift their pigments inward during transport to protect from light and stress; color returns within a few days under good aquarium lighting and flow.
We ship via 2 Day service on Mondays and Tuesdays only to ensure specimens arrive healthy. You will receive a notification with tracking information as soon as your order ships.
