The Speckled Mushroom can change colors and their appearance is extremely variable, sometimes its hardly speckled at all!

  The Speckled Mushroom Coral Actinodiscus mutabilis is also known as the Brown Mushroom, Spotted Mushroom, or Green Mushroom. These different names depict their variability. They have a smooth surface which can be decorated in several color variations, and often have widely spaced bumps or speckling . They can change color from green to a light brown and can also have iridescent edges.

  There are many variations of the Speckled Mushroom. Some will be marbled with green and brown, and may have blue or other colored pimpling. Others can also be green in the center with brown on the rest. This variety can have brown pimpling that is concentrated on the outer part, and sparse over its green center. Another variation will have bright green dots all the way around the edges, and still others can have some thin irregular lines radiating from the center.

   The A. mutabilis is very hardy and one of the best corals for both beginners and advanced aquarists. They are readily available and easy to care for. They don’t like or need high levels of light and will primarily feed off suspended micro particles from the water column. Reaching only 2-3″ (5-8 cm), they are a great addition to any nano tank, or to larger sized aquariums as well.

   The A. mutabilis propagates easily in captivity. But after splitting, the clone mushroom doesn’t necessarily always resemble the “mother” mushroom, thus giving the aquarist a variety of shades and colors. They are semi-aggressive. If they are near another coral they will cause them to loose tissue, recess, and possibly die. Acroporas will not grow in aquariums with large mushroom populations. A. mutabilis have very few predators if any.

Scientific name

   Family: Discosomatidae

   Species: Actinodiscus mutabilis

Distribution / Background

   Mushroom Coral Information: The Speckled Mushroom Actinodiscus mutabilis was described by Ruppell and Leuckart in 1828. Some names they are known for are Brown Mushroom, Spotted Mushroom, and Green Mushroom. Some general names for these are Mushroom Coral, Mushroom Anemone, Disk Anemone, Mushroom Rock Actinodiscus, Coral-like Anemone, False Anemone, Jewel Anemone, Shroom, and Mushroom.

   As far as current taxonomy, the A. mutabilis is listed under Actinodiscus and not Discosoma, according to the 2007 taxonomy list. The taxonomical identification of mushroom corals has a history of limited and dated information which is often of dubious value and sometimes incorrect. Mushrooms corals have no fossil records and studying the physical aspects has proved to be not very reliable for identification. Modern methods using DNA and RNA testing to deduce the sequence of genes, though more reliable, is not readily available.

   Where Mushroom Corals Are Found: The Actinodiscus mutabilis are found in most oceans.

   Mushroom Coral Habitat: The Speckled Mushroom prefers low current, and shallow to mid-depth waters. They are primarily found in nature at depths below 32 feet (10 m), although some are found in shallower brighter waters as well. Like other mushrooms, they prefer the shaded areas, indirect sunlight, where they like to grow on dead corals, rubble, and between coral heads. They feed on micro particulate items in the water column.


   The Actinodiscus mutabilis is not on the IUCN Red List for endangered species


   What do Mushroom Corals look like: These Coral Mushrooms Actinodiscus mutabilis are basically a coral without a skeleton and their internal structures are the same as stony corals. The top of their body or the upper surface is called the oral disc. The stalk area, which is very small, is called the column and it is located just above the pedal disc, which is where they attach to surfaces.

   The A. mutabilis can actually change color from green to light brown and can have specking in contrasting colors or even iridescence. At times they can also be marbled with green and brown with blue or other colored pimpling. Another variation can be green in the center with brown on the rest with brown pimpling that is concentrated on the outer part, but sparsely over the green center. They can also have bright green dots all the way around the edges and can have some thin irregular lines radiating from the center, from 1 to several.

   Though they lack the long feeding tentacles to capture prey, their surface does hold several types of stinging cells.   They can actually warp the surface of their oral disc to change the water flow over them to direct particulate and flocculent material toward their mucous center for absorption. At times they will make a trumpet shape. This is thought to be formed when they are needing nourishment, or if the light level is low, or is of low quality due to age.

   Mushroom Coral Life Cycles: The Speckled Mushroom can grow to 2-3″ (5-8 cm), but their life span is unknown.

Difficulty of Care

   Mushroom Coral Care: The Speckled Mushroom is easy to care for and does not like or need high levels of light. They should be kept in shaded areas in tanks with high output lamps. If they are not shaded, they turn all brown and fail to thrive. Some will just float around the tank until they find a nice shaded area or have an unpleasant encounter with a pump. They also cannot handle high or high to moderate water flow. But they can handle higher levels of nitrate than SPS and LPS corals.

Foods / Feeding

   Mushroom Coral Feeding: The Speckled Mushroom is a carnivore. In the wild, these corallimorphs are well equipped with nutritional alternatives for their well-being. They derive nutrition from their symbiotic algae, zooxanthellae, that dwells within their tissues and they eat suspended micro particles out of the water column. They can actually warp their surfaces to change the water flow over them to direct particulate and flocculent material toward their mucous center for absorption.

   In captivity you can feed your A. mutabilis newly hatched artemia once in a great while. But really, it is the nutrient level in your tank that they will thrive in, and not direct feedings.

Aquarium Care

   Water changes of 10% bi-monthly or 20% a month are typical. Provide a reef environment with proper magnesium levels. Some claim proper iodine levels are beneficial also. Due to their toxins, active carbon is a good idea with larger colonies of mushrooms. Do not over skim since the A. mutabilis need nutrients to survive on and will not do well in a pristine environment.

Aquarium Parameters

   A typical live rock/reef environment is what is needed for your Speckled Mushroom. Provide rubble or dead coral and live rock for them to have something with which to attach their pedal disc. They do not do well with strong water movement, so direct the power heads and intake nozzles away from them. As they can float around when looking for a place to settle, it’s a good rule of thumb to have all of your pumps covered. Most good quality pumps have guards on them.

  • Minimum Tank Size / Length: Nano tank of 1 gallon or more
  • Marine Lighting: Low, moderate for specimens from brightly lit shallow waters
  • Temperature: 72° – 83° F (22° – 28° C)
  • Salinity / Specific Gravity: 1.023 to 1.025
  • Water Movement: Low / weak
  • Water Region: Bottom of the aquarium

Compatibility and Social Behaviors

   The Speckled Mushroom is semi-aggressive if they are near another coral. They will cause other corals to loose tissue, recess, and possibly die. Acroporas will not grow in aquariums with large mushroom populations. Make sure to leave 6 – 8 ” between your mushrooms and other corals. Watch the growth rate since the A. mutabilis will overgrow and kill any nearby corals.

   Mushroom Anemones will tolerate their own species and usually other Mushrooms. In the wild many species of Mushroom Corals occur together in large groups. In captivity A. mutabilis will get along with their own species, but may not tolerate mushroom species outside their colony. Even in one genus, if the color is different or a different species, the weaker mushroom will detach and find another location. Strong water movement will cause them to detach as well.

Sex – Sexual differences

   No sexual difference in appearance is known.

Breeding and Reproduction

  • Mushroom Coral Reproduction:
       Corallimorphs reproduce in 4 different ways. The first three ways, asexual budding, laceration, and division/fission, are successful in the aquarium as most hobbyists soon discover. Budding is where individuals are formed from particles divided off from the pedal disc. Similar to budding, laceration happens when they move slowly over the surface and leave behind small pieces that will eventually form into mushrooms. Division or fission is where an individual divides down the center and forms two animals.
       Sexual reproduction is where eggs and sperm are released into the water column. They unite and form free-swimming larvae which are initially plankonic, and them settle and adhere to the substrate. Sexual reproduction has not been well documented, and has not been observed in captivity. Presumably modern filtration methods are inhospitable to free swimming larvae.

  • Mushroom Coral Propagation:
       Mushroom corals can be easily propagated in captivity by cutting individual polyps into several pieces. Placed the pieces on a gravel substrate with low water flow. They will attach themselves to pieces of gravel. Later they can then be super glued to a suitable substrate such as a reef plug. It has been stated that the warmer end of their temperature spectrum encourages reproduction.

   For details on how to propagate your mushroom corals see Mushroom Corals: Mushroom Coral Propagation

Potential Problems

   The A. mutabilis are disease resistant, and only affected by improper husbandry. Problems for the most Corallimorphs are pretty minimal unless your lighting, water movement, feeding and water quality are improper for these animals. A sign of this is if your coral mushroom detaches to look for “better conditions” to settle in. They have very few predators if any.


   Mushroom Corals for Sale: The Speckled Mushroom, Brown Mushroom, Spotted Mushroom, or Green Mushroom A. mutabilis can be found easily online and at pet stores, as well as from frag farmers and most reef clubs. At times they can be listed under Actinodiscus sp. Online they are $29.00 USD or more depending on the size of the rock they come on and the color.