{"product_id":"mermaids-fan","title":"Mermaid's Fan Macroalgae (Udotea) - Reef Genetics","description":"\u003c!-- topshelf-macro-seo:v1 --\u003e\n\u003cp\u003e\u003cstrong\u003eMermaid's Fan macroalgae (\u003cem\u003eUdotea\u003c\/em\u003e sp.) grows an upright green fan from a holdfast anchored in sand.\u003c\/strong\u003e It is a calcareous ornamental, not a tumbling Chaeto substitute. The fan-shaped thallus adds a natural seagrass-flat look while using nutrients and calcium to build tissue. The previous product copy incorrectly described this species as Chaetomorpha; this care guide corrects that distinction.\u003c\/p\u003e\n\u003ch2\u003eMermaid's Fan macroalgae quick care facts\u003c\/h2\u003e\n\u003ctable\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth scope=\"row\"\u003eScientific name\u003c\/th\u003e\n\u003ctd\u003e\n\u003cem\u003eUdotea\u003c\/em\u003e sp. (commonly \u003cem\u003eU. flabellum\u003c\/em\u003e in the aquarium trade)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth scope=\"row\"\u003eAlgae group\u003c\/th\u003e\n\u003ctd\u003eCalcareous green macroalgae\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth scope=\"row\"\u003eCare level\u003c\/th\u003e\n\u003ctd\u003eModerate\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth scope=\"row\"\u003eLight\u003c\/th\u003e\n\u003ctd\u003eBright\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth scope=\"row\"\u003eWater flow\u003c\/th\u003e\n\u003ctd\u003eGentle to moderate\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth scope=\"row\"\u003eGrowth rate\u003c\/th\u003e\n\u003ctd\u003eSlow to moderate\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth scope=\"row\"\u003eBest placement\u003c\/th\u003e\n\u003ctd\u003eFine aragonite sand bed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth scope=\"row\"\u003eNutrient export\u003c\/th\u003e\n\u003ctd\u003eLow to moderate\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth scope=\"row\"\u003eFood value\u003c\/th\u003e\n\u003ctd\u003eLow; calcification discourages many grazers\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth scope=\"row\"\u003ePortion\u003c\/th\u003e\n\u003ctd\u003eOne rooted natural specimen\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch2\u003eWhy keep Mermaid's Fan macroalgae?\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003eCreates an upright fan-shaped accent in a planted reef or sand-bed display.\u003c\/li\u003e\n\u003cli\u003eAnchors with rhizoids instead of drifting through the aquarium.\u003c\/li\u003e\n\u003cli\u003eIts calcified tissue is less attractive to many herbivorous fish.\u003c\/li\u003e\n\u003cli\u003eCan produce new fans from an established holdfast under suitable conditions.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2\u003eLighting, flow, and nutrients\u003c\/h2\u003e\n\u003cp\u003ePlant the holdfast in fine aragonite sand and leave the green fan exposed. Provide bright light and gentle-to-moderate flow; do not tumble it. Because Udotea deposits calcium carbonate, maintain stable calcium and alkalinity. Keep some nitrate and phosphate available, but make corrections from test results rather than dosing blindly.\u003c\/p\u003e\n\u003ch2\u003eRefugium or display tank?\u003c\/h2\u003e\n\u003cp\u003eA mature sand bed is the natural placement. Choose a spot where the base will not be uncovered by strong flow, burrowing fish, or constant rearrangement. Mermaid’s Fan can grow in reef systems, but its rooted habit makes it a display ornamental rather than a typical bare-bottom refugium crop.\u003c\/p\u003e\n\u003ch2\u003eHarvesting and pruning\u003c\/h2\u003e\n\u003cp\u003ePrune only damaged or declining fan tissue and avoid disturbing the buried holdfast. Healthy new fans may emerge near the base. Unlike fast refugium algae, Mermaid’s Fan is not grown for frequent biomass harvest. Repeated heavy trimming or uprooting can prevent the plant from establishing.\u003c\/p\u003e\n\u003ch2\u003eTroubleshooting Mermaid's Fan macroalgae\u003c\/h2\u003e\n\u003cp\u003eA loose specimen cannot stabilize if the holdfast is repeatedly exposed. Replant it in fine sand and reduce direct flow. Pale growth can follow light or chemistry instability; soft deterioration can follow shipping stress or burial of the fan. Because the genus can reproduce by releasing cells, promptly remove fully deteriorating tissue.\u003c\/p\u003e\n\u003ch2\u003eHow Mermaid's Fan macroalgae compares\u003c\/h2\u003e\n\u003cp\u003e\u003ca href=\"\/products\/green-staghorn-codium-macroalgae\"\u003eGreen Staghorn\u003c\/a\u003e provides branching display structure attached to hard substrate, while \u003ca href=\"\/products\/sea-lettuce-reef-genetics\"\u003eSea Lettuce\u003c\/a\u003e is a fast leafy nutrient exporter. Mermaid's Fan is the rooted, calcified choice for an open sand bed. Use \u003ca href=\"\/products\/chaetomorpha-macroalgae\"\u003eChaeto\u003c\/a\u003e when filtration is the main goal.\u003c\/p\u003e\n\u003ch2\u003ePortion sizes, shipping, and acclimation\u003c\/h2\u003e\n\u003cp\u003eEach order contains one natural rooted specimen, so exact fan size and shape vary. Float the sealed bag for temperature, rinse in discarded tank water, and inspect it. Plant only the holdfast in fine aragonite sand, leave the fan uncovered, and begin under reduced light before moving to the final bright setting.\u003c\/p\u003e\n\u003ch2\u003ePairs well with\u003c\/h2\u003e\n\u003cp\u003e\u003ca href=\"\/products\/illumagic-pixel-refugium-dalua\"\u003eIllumagic Pixel Refugium Light\u003c\/a\u003e for full-spectrum light and \u003ca href=\"\/products\/calcium-checker-colorimeter-hanna-instruments\"\u003eHanna Calcium Checker\u003c\/a\u003e, \u003ca href=\"\/products\/alkalinity-checker-colorimeter-hanna-instruments\"\u003eHanna Alkalinity Checker\u003c\/a\u003e, and \u003ca href=\"\/products\/marine-magnesium-checker-colorimeter-hanna-instruments\"\u003eHanna Marine Magnesium Checker\u003c\/a\u003e for stable calcifying conditions.\u003c\/p\u003e\n\u003c!-- \/topshelf-macro-seo:v1 --\u003e","brand":"Top Shelf Aquatics","offers":[{"title":"Default Title","offer_id":49941856977194,"sku":"548466","price":19.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0783\/0873\/7322\/files\/mermaids-fan-macroalgae-for-sale.webp?v=1790863439","url":"https:\/\/topshelfaquatics.com\/products\/mermaids-fan","provider":"Top Shelf Aquatics","version":"1.0","type":"link"}