My Toadstool Coral, Is It Rotting?

The toadstool coral or mushroom leather coral, (Sarcophyton sp), are hardy and very decorative. They can grow to quite a size but this varies and is not usually a problem. These corals are suitable for a new aquarist, and, with some experience under the belt, are easy to propagate by cutting. More advanced aquarists who are ‘into’ soft corals often have a toadstool in their collection.

As the name implies, they look a little like a toadstool, but often have convolutions on the head. The usual open state is that they are expanded and many polyps extend from the upper surface of the head. If there is a clownfish in the aquarium, they will sometimes adopt a toadstool coral as home, nestling in among the polyps, which doesn’t seem to harm or bother the coral.

Sarcophyton sp. close down in the same way as other corals. They deflate and have their polyps withdrawn. Sometimes the polyps are only partially extended, and sometimes diffferent areas are not extended at all, giving a clumpy effect.

The question arose because a toadstool that had been healthy had closed up for a while. The coral had closed down normally, had opened the next day but with less polyps extended, the next with even less, and the next with none. When open it was noticed that the coral had discoloured patches on the surface of the head, and these areas had a waxy appearance. The coral stayed closed for a day or two, then began opening in reverse sequence, more and more polyps extending as time passed. Surface skin was sloughing off in the water current. This skin, not large in area, did not seem to affect any other coral. The discoloured areas disappeared and the polyps became fully extended and all present once again.

The coral was not rotting as the aquarist had feared. It was simply getting rid of surface skin. Presumably this is a possible routine occurrence on this species of coral, perhaps a means of ejecting any unwelcome passengers such as algae, accumulated dirt or even parasites.

A coral that is behaving in a different manner to normal needs observation over time. Some soft corals can stay closed for a week or more, then inflate and be as beautiful as ever.

If the period of closure seems just too long, and rot does seem to be a problem, then the coral can be carefully checked – rotting should be apparent if the area is gently squeezed with the fingers as it will tend to be excessively squashy and may break up (generally touching corals should be minimized, not touching at all in normal circumstances). Rotten parts can be cut away with a sharp pair of scissors or a suitable knife, cutting slightly into the good flesh to ensure all rot is removed. All things being equal the remarkable regenerative power of the coral will come into play.

  1. does anyone have any pictures of a rotting soft leather coral and/or a picture of a “molting” one??

  2. I bought a leather soft coral…on Saturday, by Sunday midafternoon it was “molting.” The sites I looked at said that it was normal; today…two days later, it looks dead. I was hoping that I could find a site that would give me a picture of what it should look like when it was okay and when it was rotting….any help would be greatly appreciated.

    BTW…all water tests and temperature tests are within normal limits or better.

  3. Hi Perry.
    When a leather coral is moved from one aquarium to another, it closes up as this is a defence response. When it re-opens this can be only partial, sometimes inflated but without any polyps showing. Then it could start to ‘shed’ – that is a skin like substance comes off the coral. This is likely to be a response to the change of location and the change in seawater.
    Overall, leather corals are hardy as corals go.
    You advise all your water tests are fine, so I suggest wait and watch.
    If there is an area of severe discolouration and the flesh in the area is soft and crumbly, that is rot.
    I’m sorry we haven’t a picture as requested.
    Sometimes a soft coral might look shrivelled and lifeless in my reef, and may stay so for many days, then hey presto it’s back.

  4. yeh i bought mine 2 days ago …. it seemed eager to expand on the first day and came out awsomly …but yesterday it was half in and then half out and then in completely …. today it his been in completely . i created waves of motion with my hand to waft water over the surface ,and a scin like material started coming off..
    so im prosuming this is the normal thing it does when introduced to a new tank

  5. Hi Dan,

    It is quite common for a toadstool to ‘shed’ it’s skin. Mine does it all the time. When you first see it you do get a bit scared though!

    It’s not just when it is first introduced to the tank though, mine does it all the time. I think that it is a thing the coral does to clean it’s outer skin of debris, waste, mucus etc.

    I have noticed that after it has shed that it looks a load better and also looks bigger.

    Rotting can normally be determined by slightly creating waves near to the effected part. If it is rotting the area will start to break away.

    My recommendation – cut the effected area away with a sharp scalpel and discard it. Keep a close eye on the coral over the next few weeks and cross all your fingers and toes.

  6. cheers pete

    haha my brittle star lives in the water outlet of my skimmer lol
    got him out the other day but he was straight back in there :p
    thing is he aint goona be able to feed very well in there is he

  7. Hi Dan,

    Obviously likes it in there then doesn’t he?

    Don’t worry about him getting hungry. When he wants food he will soon come out.

    Trouble is you can’t watch hime in there!


  8. I’ve got a small toadstool that I’ve had for over 6 months now, and it’s been doing worse and worse the entire time. Right now it is small and grey and looks very bad. Why would this be happening? I don’t think I’m doing anything wrong, as the rest of the corals in the tank are doing well.
    Any help would be greatly appreciated.

  9. Hi Morgan

    Do you have a picture that you could either email through to us or upload to the forum as it would be a lot easier to assist if we could see it in person so to speak.

    It could be a number of things – it could be water flow, water parameters, bugs etc however it is very hard to diagnose without seeing it.

    Could you also let us know your water parameters etc.



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