The Rhodactis Mushrooms are a group of soft, fleshy, polyp animals closely related to stony corals. They exhibit unique and varied colors, shapes, textures, and sizes. Rhodactis are easy to care for and adaptable to multiple common aquarium environments. If you are looking for a colorful, easy, photosynthetic polyp to enjoy almost anywhere in your saltwater aquarium, the Rhodactis mushrooms may be the answer.
Nomenclature
Common and trade names for species in the Rhodactis genus include but are not limited to; hairy mushroom, hairy mushroom anemone, and fuzzy mushroom. Elephant ear mushroom is usually reserved for the shorter tentacled mushrooms of the genus Discosoma, but are sometimes applied to Rhodactis.
Rhodactis is a genus of mushrooms belonging to the family Discosomidae. Another member of this family includes the genus Discosoma (smooth elephant ear mushrooms).
Discosomidae belongs to the order Corallimorpharia, which are closely related to anemones (order Actiniaria) and stony corals (order Scleractinia).
Most corals are split into two subclasses. The first is defined by having eight tentacles surrounding their polyps (Octocorallia) and the second having six tentacles surrounding their polyps (Hexacorallia).
Rhodactis and other Corallimorphs belong to the subclass Hexacorallia. Stony corals are also in Hexacorallia, while soft corals are in Octocorallia. Therefore, Rhodactis mushrooms are more closely related to stony corals than soft corals.
While these mushroom-like polyps are classified in the same phylum (Cnidaria) and class (Anthozoa) as many corals, they are classified themselves as Corallimorphs, which are not corals. Take this into consideration when viewing “mushroom corals'' for sale at your local fish store.
Animalia (Kingdom)
Cnidaria (Phylum)
Anthozoa (Class)
Hexacorallia (Subclass) Octocorallia (Subclass)
Corallimorpharia (Order) Soft Corals
Anemones
Stony Corals
Zoanthids
Rhodactis mushrooms were originally described before their family, order, or subclass was officially classified. Specimens collected from Australia were described to western science in the archives of the Museum of Natural History in Paris by Milne, Edwards, and Haime in 1851.
Description
Rhodactis are extremely diverse in size, texture, shape, and color. They can range in size from less than one inch to nearly two feet in diameter. While most Rhodactis have larger tentacles and appear hairy or fuzzy, the size and shape of those tentacles vary widely.
There are hundreds of color morphs of Rhodactis with no two morphs having the exact same pattern. They can come in combinations of green, brown, tan, pink, and purple. Most Rhodactis' body coloration differs from their tentacle color. Rhodactis are an easy option when the goal is adding diverse color in the form of a hardy species.
Distribution
Rhodactis are found in the Indo-Pacific reefs of Fiji, Tonga, the Solomon Islands, and the Great Barrier Reef.
Habitat
Rhodactis are found naturally living in bays, lagoons, channels, slops, and shallows in and around reefs. They proliferate amongst dead coral, rubble, and in between living coral colonies.
Aquarium Habitat
Rhodactis can be placed nearly anywhere in the aquarium where lighting and flow is suitable. Getting them to attach and stay can be a challenge. Usually, mushrooms are sold already attached to rocks or plugs.
Mushrooms will detach and float around the tank if they are not happy with their surrounding lighting and flow conditions.
Rhodactis range from peaceful to aggressive in terms of territory. Most will be fine with members of their own species. Like with most corals, Rhodactis mushrooms need room to grow.
Lighting
Rhodactis do well in low (75 PAR) to moderate-high (150 PAR) lighting. Rhodactis adjust to lighting easily. They can live in high lighting SPS tanks and low lighting LPS tanks. Their color is not known to amplify under higher lighting and will still become bleached if exposed to lighting higher than 250 to 300 PAR for too long.
Flow
Rhodactis prefer low flow, but can handle indirect moderate flow. When adding Rhodactis, err on the side of caution and keep moderate to high direct flow off of them as they may choose to release and move about the aquarium.
Feeding
Rhodactis receive much of their nutrients from the photosynthetic algae in their cells. However, they are also efficient filter feeders. If you feed your tank microplankton, they will readily feed upon it. You can also target feed Rhodactis when the tank flow is shut off.
Water Parameters
pH | 8.1 - 8.4 |
Salinity | 1.023 - 1.025 sg |
Alkalinity | 7.8 - 9 dKH |
Calcium | 400 - 480 ppm |
Magnesium | 1300 - 1400 ppm |
Nitrate | 5 ppm |
Phosphate | 0.05 ppm |
Temperature | 76 - 78 degrees Fahrenheit |
Water Flow | Low |
Preferred Lighting | Low - Moderate High |
Maximum Size | 45 cm |
Life Span | Unknown |
Tank SIze | 10+ U.S. gallons |
Dispostion | Peaceful to Agressive |
Aquaculture
Rhodactis propagate asexually by developing two mouths then splitting to form two distinct polyps. This process is called longitudinal fission.
It is possible to bilaterally lacerate a Rhodactis polyp between its two mouths to speed up propagation. When practicing this procedure, watch for signs of a developing infection where the coral was cut. Also, make sure both halves of the bisected mushroom foot stay connected to the substrate.
Acclimating New Mushrooms
As with any coral or polyp, be sure to drip acclimate, then dip new specimens. Drip acclimation ensures a low stress transition which prevents infection and sickness later.
Dipping new mushrooms in coral dip will remove larger pests like worms, sea stars, snails, and crabs. Dipping new mushrooms in hydrogen peroxide or iodine prevents the transfer of bacteria and algae cells into your aquarium.
After you place your new Rhodactis into your tank. Be sure to lower lights to 50% of your normal schedule for 48 hours to acclimate even further. Also be aware of flow,' mushrooms are motile and can move about the aquarium if they find their current position undesirable.
All this acclimation may seem unnecessary to some, but my philosophy is why spend the money on these animals and not take every precaution to ensure their happy and healthy survival in your aquarium. For more on drip acclimation, check out this article.
Rhodactis Ailments
There are not any Rhodactis-specific ailments I’m aware of. However, like with any coral or polyp, infections, pests, bleaching, shrinking tissues, and die-off can become an issue if dipping, proper water quality, lighting, and flow is not maintained.
Pests
Bristleworms are known to favor Rhodactis mushrooms. If you have an infestation, be sure to check your Rhodactis for signs of predation.
The Rhodactis Mushroom Polyp
Rhodactis are a great addition to any system that has the room for these guys to grow out and show off their unique shape, texture, and colors. A mushroom colony garden is quite a sight to behold.
They do grow quickly and can be aggressive toward neighbors when territory becomes constrained, but with proper planning, Rhodactis can be a great choice.
Literature Cited
Fautin, D. G. (2013). World List of Corallimorpharia. Rhodactis Milne Edwards & Haime, 1851. Accessed through: World Register of Marine Species at: https://www.marinespecies.org/aphia.php?p=taxdetails&id=267806 on 2022-08-20
Photos
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