Mushroom Corals for the Aquarium
Of all the Cnidarians we keep in our reef tanks, "mushrooms" may be some of the most beautiful, easiest to care for and easiest to propagate of all. Unlike many of their betentacled cousins, mushrooms (also called mushroom anemones or mushroom corals or "shrooms") are very tolerant animals. Tolerant of low light, low flow and high nutrient levels (read: fish poo.) That doesn't mean you can keep them under a candle in a cup of coffee. But it does mean they are excellent "beginner corals". One caveat here; because these animals are so tolerant and so prolific, they can "take over," especially in a small tank. Further, as many saltwater aquarists mature in the hobby, they turn toward stony corals, especially SPS corals, and it can be very difficult to rid a tank of the shrooms introduced as a newbie. In particular the red form of Discosoma sp. has a mind-boggling ability to reproduce with the little buggers cropping up everywhere.
|These red mushrooms appeared in this spot in the author's tank on their own.|
As the animals divide by fission, they can cover the rock they're on. And once they do, they starting releasing from the rock and drifting to settle in new spots. You never know where one will pop up. For some aquarists like myself who want them to proliferate, this reproductive capacity is a welcome boon. But for those who don't, the mushrooms can become invasive, with Discosoma spp. being potentially much more so than the other genera.
|Four different types of shrooms in the author's aquarium. The two species in the foreground are likely Rhodactis spp. and the red and purple shrooms in the back are Discosoma sp.|
A quick note about terminology. I will refer to the entire group of animals discussed here alternately as "mushrooms", "mushroom corals", "mushroom anemones" and "shrooms". All the terms are used by aquarists and hopefully it makes the reading a little more interesting and not a little more confusing. When discussing the various genera of mushrooms, I will sometimes use just the genus and will sometimes add "sp." or "spp." If the "sp." is used, it means the mushrooms being discussed are likely from a single species within that genus. If the "spp." is used, it means the mushrooms being discussed are likely from multiple species within a single genus. This is all for the sake of conveying meaning and doesn't necessarily always conform to official taxonomic standards.
Now, let's turn our attention to the basic biology of the various species of mushrooms we keep. Mushroom anemones are considered Corallimorpharians and are sometimes referred to as "Corallimorphs." Typically, these animals can only be identified to the genus level by aquarists. And, as is often the case in reef-keeping, the genus level is the perfect level of detail to know for the purposes of keeping and discussing these animals. The three main genera of mushroom anemones kept in aquaria are Discosoma, Rhodactis, and Ricordia. Animals from all three groups have a number of basic Cnidarian characters in common including radial symmetry and a single gut opening. Rhodactis and Ricordia also have small stinging "psuedo-tentacles", while in Discosoma, these tentacle-like structures are largely reduced or lost. Mushrooms adhere to rocks with a foot just like other anemones. And, like other anemones, they can slowly wander. The column of mushroom anemones is basically non-existent. The top surface of the mushroom is called the "oral" side and the bottom is the "aboral" side, again, just like with other anemones. Finally, whether or not they use it, mushrooms have a mouth located in the middle of the oral side. These are not colonial animals in that there is no shared base of tissue under a group of mushrooms. But like colonial Cnidarians, aggregations are likely genetically identical clones formed by fission or "division" as aquarists often call it. Presumably, these animals can broadcast spawn but in aquaria, propagation is primarily through division.
The genus Discosoma is synonymous with and has replaced the genus Actinodiscus. These are the classic shrooms. They tend to be basically flat with little in the way of tentacles. They sometimes have small bumps on their surface which can be of contrasting color and they sometimes have little irregular protrusions around the margin. They do have a mouth in the middle like all Cnidarians but they really don't feed on meaty foods, deriving their energy pretty much entirely from their symbiotic zooxanthellae and their nutrients by absorbing them from the water column (this from anecdotal information/personal observation/speculation.) These animals actually need a certain amount of nutrients in the water and thrive in "dirty" tanks. Brand new or sterile tanks with ultra-low nitrates are not ideal for mushroom corals. Though they may survive, they'll likely not proliferate the way they can in more mature tanks with higher bioloads.
|A purple form of Discosoma sp. in the author's aquarium. Like the red ones above, this little guy just popped up here.|
The Rhodactis shrooms are equally hardy and tolerant to their Discosoma cousins. They can tolerate similar low-light, low-flow, high-nutrient environments though they seem to be somewhat less tolerant of very low light than Discosoma. They also tend to divide somewhat less vigorously than Discosoma. Rhodactis mushrooms typically have small "psuedo-tentacles" densely distributed on their surface which give rise to one of their common names, "hairy mushrooms". These structures may be indicative of an ability to capture prey and indeed, unlike Discosoma, the Rhodactis mushroom will eat meaty foods with the largest species even being reported to capture small fish though that is unconfirmed by the author. Here are some Rhodactis mushrooms eating pelletized fish food that has fallen on their oral surface during a fish feeding. You can see three of them on the right are closed up around their food.
|Rhodactis mushrooms feeding.|
Of the three genera commonly kept, Ricordia are the most particular mushroom anemone in terms of their environmental requirements and also, somewhat surprisingly, their hysterical and wholly uninformed political views. I don't have access to any photos of Ricordia spp. shrooms as the Ricordia florida specimens I once had wasted away. I now believe that was likely from a lack of feeding and perhaps inappropriate light. Ricordia spp. and especially Ricordia yuma, are widely considered to have the most specific lighting needs of any mushroom anemone. Any aquarist introducing yumas into their tank should be prepared to adjust their height until a healthy light level is determined. Yumas are also generally the most expensive mushrooms around so I've never tried them. They can be differentiated visually from Ricordia florida by the presence of psuedo-tentacles on the oral disc or mouth itself. Florida lacks these. Ricordia yuma also presents the greatest and most spectacular array of colors in the mushroom world. I'll leave it to you and your search engine of choice to confirm that.
As has been discussed above, mushroom anemones are generally not fussy critters. I'm going to focus these keeping notes on Discosoma and Rhodactis species with the understanding that Ricordia mushrooms are somewhat more demanding over-all in terms of lighting and feeding.
Mushroom anemones appreciate the same basic reef tank parameters as any other animals in terms of salinity, temperature, ph, etc. with stability in all areas being paramount. But more than perhaps any other commonly kept Cnidarian, mushrooms can handle very high nitrate and particulate levels in the water. In fact they seem to thrive on it. Any time I've gone too long without a water change, most of my corals start to look funky but my mushrooms look freakin' amazing! They get huge, their color deepens and they just generally look happy. And they divide more frequently. All these attributes make Discosoma spp. and Rhodactis spp. mushrooms perfect beginner corals. This shouldn't be confused with "disposable corals." Beginners need to do their homework in books and online, not by killing things. These animals do require a modicum of attention and care. But they're pretty much the easiest reef tank animal there is.
All of the common types of reef lighting are fine for shrooms with higher intensity lighting requiring lower placement in the aquarium. Don't fry your shrooms, dude! Mine are kept happy under T5HOs in my 75 gallon from the bottom of the tank to the top. I've seem mushrooms thrive under metal halide, power-compact and LED lighting as well. Ricordia species generally require a little more light though, as mentioned, this is not a genus I've had success with. I suggest additional reading for anyone considering Ricordia mushrooms for their reef.
As is mentioned in the caption above, mushroom corals are fairly non-stingy and mixed well almost all other non-stony corals. They look awesome on rocks with a mix of color morphs and maybe some zoos.
|A mixed mushroom/zoanthid rock in a holding tank. The needles are holding new mushrooms in place until they attach. We'll discuss this method and others in the propagation section.|
Discosoma spp. mushrooms do not need to be fed. They only need decent reef lighting and sufficient nutrients in the water to survive, grow and reproduce. Rhodactis spp. mushrooms appreciate the occasional feeding of meaty foods or even fish pellets or flake. When they're feeding, you'll see them close up around their food making them look kind of inside-out. Recordia spp. also feed and likely need even more meaty foods than Rhodactis spp.
Propagating Mushrooms a.k.a. Frankenshrooming
Propagating mushroom anemones in the aquarium pretty much takes care of itself provided their basic requirements are met with aggregations forming rapidly from a single shroom. In a holding tank or propagation facility, a more strategic approach might be desirable and to that end, I present a couple of options.
The first technique is to attach free-floating or salvaged shrooms to a rock using stainless steel hypodermic needles. This allows the aquarist to attach many mushrooms exactly where desired. This technique can be used only when the mushroom is unattached to any hard substrate. If the animal is attached to a small piece of rock or similar, this rock may be glued to another, larger rock by standard means. But if the mushroom is found drifting in the tank or if it is removed from a smooth, hard surface like egg-crate or aquarium glass with a razor blade, it is a good candidate for this needle technique.
|Mushrooms attached to undesirable substrate like this standpipe in a holding tank are good candidates for removal with a razor blade and attachment with a needle.|
|This rangy little red number amongst the muck and mire of the bottom of a holding tank will make a lovely specimen once it's removed and attached to a rock with others of its kind.|
A couple items should be noted. First, even though the needle you'll use is stainless steel, that doesn't mean it won't ever rust, especially, it seems, if the needle has been bent. Needles should only be left in the water for a few days which should allow the animal to attached. And needles should be inspected for rust daily. Rust is definitely negatory in the reef tank environment. Second, needles are pokey and you could inadvertently inoculate yourself with shroom juice like the unfortunate aquarist from Hoboken, N.J. pictured below. Be careful.
Luckily this ill-fated aquarist was taken to a local hospital where an antidote of highly repressive cultural values was administered just in the nick of time.
|A breeder net like this with a long piece of foam wrapped around it for floatation is useful in any number of applications in a holding, propagation or grow-out tank. This one holds salvaged shrooms ready for pinning.|
|This fist-sized rock with lots of tiny holes in it is perfect for this application.|
|This beautiful Cnidarian is about to have a new home.|
|The pin is in. Don't worry, it's going between my fingers.|
|Ladies and gentlemen, we have attachment!|
Another approach is to lay out multiple mushrooms first and then pin them all. All of this is done out of the water on a clean, stable surface.
|Salvaged red shrooms laid out for pinning to a rock.|
|Putting in the needles. Note the bent needle on the left. This was before I discovered thicker, shorter needles were far more stable for this application.|
|And back into the holding tank while the mushrooms attach.|
Another method of attaching unattached shrooms to solid substrate is to line the bottom of a breeder net like the one pictured above with small pieces of rock rubble and toss in a bunch of shrooms. Once the mushrooms attach, the pieces of rubble may be glued to larger rocks by standard means. This approach has the advantage of a bit less labor and materials but I think the needle method allows for speedier and more purposeful creation of displayable specimens. Finally, some aquarists will attach free shrooms to a rock by rubber-banding them loosely in place until they attach. I haven't tried this method but it sounds reasonable.
This propagation technique is useful when the mushroom is attached to a desirable substrate but accelerated division is sought. It involves slicing the mushroom in situ with a razor blade. Care should be taken to always slice through the mouth in the center. It is presumed this aids the animal's ability to heal and become two mushrooms. This technique may be used to create two mushrooms from one but reports of successfully creating four or more new mushrooms from a single shroom are not uncommon. Always slice through the center regardless of the number of clones created.
|A few mushrooms attached to a piece of dead coral skeleton make a good candidate for my slicing experiment. Many aquarists have reported good outcomes with this method.|
|Ye ol' razor blade. Careful, they're widely considered sharp!|
|Making the cuts. Remember, regardless of the number of pieces created, every cut must bisect the animal, passing through its mouth, to maximize chances of success.|
|A cut mushroom ready to go into the holding tank for healing. I'm not sure exactly how long that will take but I would estimate 1-2 weeks based on how fast they divide naturally.|
I haven't tried this technique, perhaps because I don't want to pay the cost of a good divorce attorney, but supposedly you can toss a few shrooms in a kitchen blender, pulse a couple times and pour the slurry over rock rubble to create a gajillion new little shrooms. Sounds pretty reasonable but you and your domestic partner(s) will have to be the last word on that for you.
Mushrooms anemones are a fun and beautiful group of animals to keep in your reef tank. They're easy to care for and reproduce readily and rapidly. Remember just a couple of key aspects to their husbandry, namely that they need low to moderate lighting and nutrient-rich water, along with basic reef tank parameters, and you should be well on your way to a groovy little shroom garden.
The information presented here is largely from my own experience. I have also gained information and insight regarding the care and propagation of Corallimorphs from various books and online resources.
|Needled shroom rocks in holding.|