Leather troubles....Allelopathy?-01/30/08 Hi Bob, For the past several weeks I have been experiencing problems with all my leathers. The first leather I noticed that was in trouble was my Toadstool, which I had for over two years. It detached from the rock and then quickly shriveled away. The next leather issue was what I believe is a green tree coral. I got this leather as a frag about a year ago. It grew to about three inches tall and then all of the limbs fell off one by one. Strangely enough I have fragged the limbs and they are doing great, <huh... good> but the original trunk has still not started any new growth. <Is it still alive?> Next in line was my year old Fiji Yellow. The yellow leather closed up for over three weeks and looked as if small bites were taken out of it. No foul play suspected. The yellow has now opened twice as big and all injuries healed. Finally my five year old stubby finger leather has begun to suffer. It appears that four or five fingers are burned to the base and another almost appears as a flesh wound. I would really like to avoid any further injury to this leather if possible. Is there any thing I can do? <It's hard to say without knowing what is causing this.> I am assuming that it is some sort of allelopathy? <It could be.> I have read multiple articles about coral aggression and allelopathy but not sure as to which ones are the culprits. <There may not be one culprit so much as just a bad combination of tank mates.> Could it be growing pains between only the leathers? I originally thought it was a wall of frogspawn which took up the entire top left hand side of my tank. I have since sold a good portion of it. I'm still not sold on that theory though. <These things can bee quite difficult to figure out specifically.> I then thought it could be the large Maze Brain next to the Stubby Finger leather, but that would not account for the injury to the other leathers. <Hmm, maybe, but as far as allelopathy goes, I would expect the leather corals to hurt the maze brain.> I believe that the Maze Brain uses its sweepers rather than chemical warfare. <It's possible.> The leathers are about three inches apart from each other and the Stubby Finger leather is about four inches from the Brain <This is close enough to be in range of sweepers.> (both have been paired together for years). <This means nothing really. For one thing, it's not unheard of for corals not to display sweepers for years. Also, corals change/adapt/grow. Just because they've been playing nice for years now, doesn't mean they are now or always will. Even the addition of other leathers may be affecting their dynamic/interaction/over all level of "hostility." These things are so poorly understood even in the wild. You can imagine how little is known about them in captivity.> I'm not sure if I should try to move the leathers further apart or to remove some mushrooms that are close by. Is there a specific type of coral that would cause the above symptoms even if the corals were on opposite ends of the tank? <Some leathers are toxic enough to affect corals anywhere in the same tank system as them.> About my tank: My 125 gallon reef has been established for almost eight years now. I have 6 six foot VHO bulbs, three actinic and three aqua suns. Two main pumps 1800 and 1200 gph. They are controlled via two SCWDs and four returns. The actinic lights come on an hour before and after the main lights. Temp is between 76 - 78 degrees. I have a wet dry sump, but plan on purchasing an ADHI refugium shortly. <cool> For the time being I have a small basket of Chaeto algae in the main tank for nutrient control. 15 gallon water changes are done weekly. I am using an AquaFX RO/DI system for RO water. Salinity level is at 1.025; PH 7.8; Nitrates and Nitrites are at 0. Alkalinity is a little on the low side. I am starting to use a buffer to bring it up. <sounds good> I also skim and use activated carbon. <Maybe more activated carbon would help.> The only other additive I use is marine snow. <a useless product> I also have 150lb of Fiji live rock. Last but certainly not least, I just wanted to say thank you to both you and Anthony Calfo for guiding aquarists through an extraordinary hobby! <Not Bob here, but will pass along the thanks...> Your book "The Conscientious Marine Aquarist" was the very first book I purchased when I began this hobby almost ten years ago. <Was my first book purchase too. :-)> Since then I have followed up with "Reef Invertebrates" and Anthony's "Book Of Coral Propagation". I consider you both invaluable assets to the hobby. Thanks for the years of help and for saving me a small fortune by constantly emphasizing research and education. Thanks Again! Dave Gambone <De nada, Sara M.>

Bleached Sarcophyton 1/23/08 Hello Crew! <Kirk> As I was getting ready for a good nights sleep last night I gazed into my 29gal softy tank and to my horror noticed that my Sarcophyton (ehrenbergii? Toadstool shape with polyps primarily around outer edge of the head) was looking very white. It has a good 6" head and was uniformly discolored and I have 2 small frags from this one that are showing the same signs. My Calcium test kit ran out about 2 weeks ago and I have been lax in getting a new one. Well, I got one today and my calcium was at 250ppm. I know, Yikes! <No big deal; easy to rectify> I also noticed today that just a few of my mushroom polyps looked a little bleached around the edges as well. <Oh... in the same small system...> The pumping xenia and Zoas in the tank all looked fine. Is this bleaching typical with low calcium or should I be looking for something else? <Mmm, yes... very likely a "cascade effect"... the low calcium or whatever caused it, stressing the Cnidarians... their reactions poisoning each other...> My light fixture went out about a month ago and I replaced it with an identical setup (dual PC, 1 10k, 1 actinic, 65W each). At first I thought this might be the culprit but it seems like it bleached out almost overnight. One other thought, I have a very small green Zoa (2 polyps) <... Irk... even more toxic> that broke off from the main colony and I was able to rubber band it to a piece of rubble and it is starting to takeoff. The other day I moved it closer to the top of the tank to get some extra light, well, apparently somebody got a little clumsy and knocked it to the bottom of the tank into the sand upside down. I noticed this first thing in the morning yesterday and replaced it in a more stable spot. Only the moon lights were running when I did this so I don't know if the Sarcophyton looked white at this time or not. <The Zoanthid... most likely the primary instigator here> I have bumped up water changes and upped my dose of SeaChem reef complete to boost calcium back to normal levels but don't want to over do it and shock anything. <Good idea> Other tank specs: Nitrate: 0 Nitrite: 0 Ammonia: 0 Ph: 8.3 KH: 8 Other Stock: 2 ocellaris clowns Bi-color blenny Skunk cleaner shrimp Serpent star Blue / scarlet leg hermits Nassarius / turbo snails Any thoughts would be greatly appreciated. Thanks, Kirk <Mmm, do peruse here: http://wetwebmedia.com/cnidcompppt.htm and the linked files above... to gain insight, a gist of what is probably occurring here. Bob Fenner>
Re: bleached Sarcophyton 1/23/08 Thanks Bob! I almost didn't even mention the Zoa falling because it was so small, <Take a read about re this life... VERY toxic... even to humans> I'm glad I did now. I guess it just goes to show that no detail can be too small and even the smallest creature can have a big impact in a small system. Thanks for the reference, I will pay particular attention to properly securing individuals in the future. <Ahhh, BobF>

Devil's hand leather coral.... hlth./appearance, spelling and reading   01/22/2008 Hey guys and gals, I have extensively used this site to help me in my tank endeavors..... really got to reading after getting so much bad info at LFS and on the internet.... plus, by reading, you don't get yelled (virtually) at like at some of the forums... this site has really helped me out a lot and I was wondering if you could answer me a hard/specific question though...... I have a 30 gallon tank, 2.5 gallon hob fuge 1 Koralia nano ph, a filter BioWheel rated for 55 gallons.... 130 watts pc....25 watts t-5... ammonia 0 nitrite 0 nitrate 10 ppm I have the scissortail goby (Gary oldman) now 4 inches ..... he needs to get out of my 30 gallon and go to my new 75 (am going to replace him with a smaller fish, possibly a filamented flasher wrasse or/and yellow clown goby).. the tank currently houses a scooter blenny 1.5 inches (Dante 5000), red Firefish 2.5 inches (sharkmonster), green clownfish goby 1 inch (nerd) and a wheelers goby 2.5 inches (cerebus) 2 cleaner shrimp (matilda and leon) a pom pom (Tyler durdan) a peppermint shrimp (Skittles) a serpent star (brad) 10 Nerite snails (the bums) 5 blue hermits (blues boys) 1 hawing hermit (Robocop), 6 Mexican Turbos (m-13), 2 onyx narcissis snails (gods disciples) 1 porcelain crab (yashimi) 1 abalone snail (golum) +1 devils hand leather and 1 mushroom polyp and some star polyps that came with a rock on accident (which is cool) the question is, my leather has not "sat down" on the rocks, he hasn't extended his base to fasten on the rocks, and he still is kinda propped up on the rock....also, he has small little polypy looking things on him, but I have seen so many pics online that the feeders are much more extended..... <Ah, yes> it is approx a foot and half from the top with the power head blowing over the top of it (not directly on it)... is there anything I should be doing to make it extend (both its base and polyps)?? if you need a pic I have one. its just about 1 meg in size.... <Something amiss with your water quality likely, or a negative interaction with the other cnidarians... and your spelling checker... the beginning of sentences are capitalized. Read here: http://wetwebmedia.com/alcyoncompfaqs.htm and the linked files above. Bob Fenner>
Re: devil's hand leather coral....  01/22/2008 just to note..... tank 6 months old... leather has been in for 2 weeks <Keep reading... learning to use your Grammar checker. B>

Distressed Leather? (Leather Coral Malady)   12/11/07 Hey, <Right back atcha! Scott F. in tonight!> I have a Toadstool Leather that I have had for a few years now. It had a yellow discoloration on the cap in the past and I put the leather in Lugol's and it seemed to take care of the problem. It has returned and the Lugol's doesn't seem to work this time. The middle of the cap has begun to decay, or I guess you could call them areas of necrosis. It hasn't look healthy for a few months now. <Hmm.. not a good sign. Something may be amiss here!> I have placed in Lugol's solution 3 times during this time period. Is there anything else that I can do? Any ideas on what might cause this? Thank you for your help. Zach Stamey <Well, Zach- this type of "necrosis" could be caused by a few different things, ranging from a localized reaction by the coral to something lodged in its tissue (such as a piece of sand, debris, etc.) to a possible response to poor or inadequate flow, or degraded water chemistry. Do some investigation and see if you can correct any problems that you find. The remedy for this condition is typically the Lugol's dips that you have already employed, or freshwater dips. If this does not seem to reverse the condition, you could always play "ER" and surgically cut out the affected area with a sharp razor blade. As you probably know, these corals generally respond well to such procedures, and heal quickly if environmental conditions (flow, water quality, etc.) are maintained. With some careful observations, minor system "tweaks", and some perseverance, you can help your Leather coral regain its former glory and thrive for years! Hope this helps! Regards, Scott F.>
Distressed Leather (Cont'd.)  12/16/07 Thanks for the info. <You're quite welcome!> Is there a limit to how many times I should try the Lugol's treatment? <I would not try it more than once a day...maybe once every other day. Not based on any scientific data, just personal experience...I don't like to overuse the stuff.> I am pretty sure that its not water quality or water movement. The water quality is maintain very well. I may have to be a surgeon for a day! <Break out the razor blade and get to work! Hope this helps! Regards, Scott F.>

Toadstool problems... Allelopathic Potential 12/04/2007 Hello and thank you for all the great work and support that WWM provides the community! <Hi Josh, Mich here and on behalf of Bob and the rest of the crew you're welcome!> I recently was given a toadstool as a gift from a local reefers tank. <Very nice!> It appeared to be fine for the first week or so and then the polyps stopped opening up. I assumed it was getting ready to slough it's protective layer due to the stress of a new system, transport etc. A day or two later it did shed it's layer, however it still did not open up. <Sometimes it takes some time.> I noticed a bristle worm exit an opening between the base of the stem and the live rock but did not think too much of it at the time since I was under the impression that bristleworms did not eat corals. <The majority do not eat living coral tissue, but most will eat necrotic coral tissue, which may be what this guy was doing.> Should I be concerned about the worm? <It is unlikely that this is a cause and effect situation.> A week later it shed again and now some of the polyps are opening up, <Ahhh, good to hear.> they are not extending as far but it seems everyday that more polyps open and they extend a little farther. <Very good!> The thing that has me concerned now is that there is a brownish crust moving up the stem of the coral. <Perhaps algae?> I can see in parts where it is sloughing off, <You might try to blow off this film with a turkey baster or even direct a powerhead towards this area.> the coral itself is standing erect and I think it has plenty of flow. In fact I moved it once because I thought it had too much flow. I have a Koralia #2 pushing flow around it plus a MaxiJet 1200 agitating the water surface above it and the output of my sump is above it also. <OK.> Tank param.s: 45-gallon reef with a MegaFlow 2 sump (bioballs removed). AquaMedic TurboFlotor 1000 inside the sump. I get some nasty black skim material in the collection cup, I empty it 2-3 times a week. <Good.> 36" Nova Extreme T5 lighting Two MaxiJet 1200's on a wave maker Koralia #2 Nitrites 0 Ammonia 0 Nitrates 10 PH 8.4 Alk 1.8 <Low, 2.5 - 3.5 meq/L is desirable.> Salinity 1.025 Temp 78.4 deg I had about 45 pounds of live rock and just added another 20 pounds of rock from an old reefers tank that had been sitting in his garage for two years ( I soaked the rocks for several days before adding). All the other corals are doing great (xenia, Shrooms, Colt leather, frogspawn, Kenya trees, Favia moon, Zoanthids, Cabbage leather, and some GSP. <Holy allelopathy Batman! You have some big players in the games of chemical warfare! Hope you running carbon and changing it frequently! More here: http://www.reefkeepingfever.com/article1.htm > I have some hermits and snails along with three peppermint shrimp that devastated the Aiptasia! <YAY!> For fish I have a six-line wrasse, <OK.> flame Hawkfish, <And you still have shrimp, hermit crabs and snail? Not likely for long! More here: http://www.fishprofiles.com/files/profiles/682.htm > and a blue lined Midas Blenny. <OK.> Should I just give it some more time I cannot find pics of toadstools with that brown stuff on the stalk, however it does not feel necrotic, although I guess I am not sure what it feels like, but the stalk is firm not mushy. <Doesn't sound necrotic to me.> Thanks so much in advance! <Welcome! Mich> Josh

Crumbling leather corals   12/2/07 Hi, I was wondering if you could help identify a problem I'm having with my leather corals (mushroom and devils hand and flower leather). I recently moved my tank because I had a new one built (old one was leaking). Before the move all my corals were doing great, opening everyday. <Just FYI, it took me several minutes to correct all your typos, grammar and spelling errors in even just these first few sentences. Unfortunately, that's less time I have to think about your actual question.> Whilst we were changing the tanks over my corals were put into huge containers. Unfortunately they were in there longer than expected due to problems with the new tank. For about 3 days, I did put lights, heaters and pumps in the containers. When moving the corals into the new tank after a couple of days I noticed they were crumbling. I have been told that this was probably an infection because they were in the containers for too long and could not shed. Part of the flower leather survived but most of it just crumbled. After this I did water checks which were all fine and then added another devils hand which seemed to be doing well but I moved it and found out that this also had holes in it there is also another mushroom in the tank which seems ok (it does not have any holes in it) but it has not opened in over a week now. <Hmm... not good.> Throughout all of this I have had green plate coral, sun polyps plus others that all survived the move and are doing well. I really do not understand what is affecting the soft corals in my tank. Before I had two t5 light bulbs and 2 normal tubes. When I changed the tank I changed to halides 250w and two t5's plus moonlights. Could this be the problem. <I doubt it's the lighting. But if you didn't properly acclimate, that wouldn't help. It sounds like your leathers have some sort of infection (maybe fungal). If they're crumbling at this point, there's not much you can do except try to save what's left.> thanks Steve
<Best,
Sara M.>

Leather Coral'¦ Closed / Male Scalefin Anthias'¦ Capturing 10/17/07 Hi there, <Hi K, Mich here.> Firstly I'd like to say this site is great and thank you in advance for your assistance. <Well, glad you like it and welcome!> Problem 1: I purchased a leather coral 3 days ago on a lump of live rock roughly 1kg in weight with over half a dozen small hitchhikers growing on it. The small anemones <Yikes! Is it Aiptasia? Does it look like anything on this page: http://www.wetwebmedia.com/aiptasidfaq2.htm and a few small corals attracted me more than the leather coral itself which is about the size of a fist. This is revealing to be a foolish mistake on my behalf. <Uh-oh!> The hitchhikers are doing well and are always open and look healthy <If it's Aiptasia, I'm not surprised.> but the leather coral itself hasn't opened up since I introduced it into the tank except once but very slightly. <Sometimes takes time.> Now that I think about it, it was closed in the display tank before I purchased it which concerns me, <Mmm, me too!> as it was in a leather coral only tank with most of the others open barring a few. About a dozen to be precise. I have placed the live rock about half way in the tank with medium water flow directed onto it. <Sounds OK.> My local aquatic store have advised me that 'it will wake up in a few days' <It can.> but I needed reassurance and decided to seek your expertise. I don't know whether it's ok or dying. <Mmm, doesn't sound sick or dying, just unhappy for now.> Please help as I do not want to lose this coral before I have experienced its beautiful splendour. <I'd give it a little time, change your carbon and perhaps do a water change. Sarcophyton corals can be quite chemically toxic to other corals and there may be other corals in your tank that are chemical producers as well. The carbon or PolyFilter will help reduce allelopathic potential.> Problem 2: In an impulse buy (I seem to do this a lot) <Not good. Is always best to research any prospective purchase.> I bought a female Scalefin Anthias around 4 months ago. I found it to be quite shy but very peaceful and pretty so I thought I'd get another one a week or so later. (I wasn't aware at this time that this species is sequential hermaphrodites) To my luck it was slightly bigger than the first. You can see where I'm going with this. <Uh-huh.> Pretty much as soon as I introduced it into the tank it started chasing the other one around. Within a month it turned into a male and became aggressive towards my clown fish too. Recently it has made a game of nipping at my cleaner shrimp when feeding in an attempt to drive them away! <Yikes!> The transformation process was interesting but definitely not worth the bother. I know that by adding more females I could calm him down but I don't want to have to do that. I am tired of this pest but despite my best efforts I haven't been able to catch the little troublemaker to take him back to the local aquatic store as he is fast and loves to hide in burrows which my blue cheek goby dug under rocks before it died. <Uh-oh!> Whatever it takes I want it out of there before it causes some irreversible damage and I don't mind taking the female back if it means the male will go. I've been told it wouldn't go into a trap and taking down 20kg of stacked live rock and risking damage to other inhabitants is my only option! Which I'm not too keen on doing for obvious reasons. Is this really my only option? <There are other options... You will want to do some further searches on the Internet and perhaps check on some bulletin board sites... One option that I have heard used with success is feeding the fish in the corner for several days and then taking a length on acrylic, placing it in the tank while feeding and trapping the in this corner.> Tank specs: 260ltr (68 gallons) Juwel tank, 2 Tetra Tec 700 filters, Vectron 2 uv filter, v2 Skim Protein Skimmer, factory standard heater (does the job), factory standard pump for water flow (not so great) and an additional power head with 850 gph flow rate, 2 marine white light bulbs (I was told these were adequate for soft corals), <I would do more research here, this doesn't sound like sufficient light to me and may contributing to your Sarcophytons' displeasure.> air block, and 20kg live rock with live sand. <Your system would likely benefit from some additional LR.> The systems been running for 6 months. <A young system.> Tank inhabitants: Yellow tang, blue tang, <Too small a system for either of these fish, let alone both of these fish!> 2 Ocellaris clowns, female Scalefin Anthias, male Scalefin Anthias, 3 cleaner shrimps, <Better in even numbers.> 12 turbo snails (started off with 6, in 6 months they have doubled!), red sea pulse coral, <Xenia?> pink pussy coral, <No idea what this might be and Googling it isn't exactly helpful.> leather coral, Japanese pagoda tube worm. <?> Please find pictures attached. <Mmm, no pics were included.> Thanks again, <Welcome!> regards K <Cheers, Mich>

Bleached Toadstool -- 10/15/07 Hi, <<Hello>> I bought a Sarcophyton leather coral 4 months ago, all has been well until I changed my bulbs. My aquarium is 240l and is fitted with 2 Aquablue+ T5s. All tests seem fine, Calcium is a bit low at 250. <<More than a 'bit' low...but simple water changes should correct>> The problem I am having is I swapped the two bulbs for 2 new ones. Since then the toadstool has been looking bleached. I was wondering if there is anything that can be done to bring it back to its original color? <<If the bulbs you replaced were 'very' old, this may be a reaction to the increased light intensity. Probably best to leave it be at this point as it has surely begun to adjust/acclimate on its own...but for future reference please read here (http://www.wetwebmedia.com/acclimcoralslight.htm). Another possibility is the Sarcophyton is reacting to an environmental/water chemistry issue. Your Calcium reading indicates an imbalance in bio-mineral elements at the least...do test for and perform a water change/water changes to bring things back in balance>> Thanks, Phil <<Regards, EricR>>

Leather Coral Help -- 11/13/07 Hi <Greetings, Mich currently in the Bahamas... being put to work by Bob> I recently bought a common toadstool leather for my nano cube. <Are quite allelopathic.> Its water parameters are all good <Vague...> and I was using the water from my 120 gallon to set it up so it won't need the 8-week maturation. I also had a green star polyp <Also quite allelopathic.> who is doing excellent. <Typically a winner in the chemical wars.> Today when I introduced the toadstool it opened up fully then the next day it went and limped to the side and was shedding a little. I know that they periodically shed but is this normal. <Maybe, but with the timing, I think it is more likely related to environmental stress.> He also has some brown chunky things attached to him but he is not decaying. <Huh? Not exactly sure what you might be talking about here... a picture might be helpful.> I got him from a great shop that had him for 5 months. He also has these two weird sections that are sort of a light green color or "Nuclear" <Mmm, "Nuclear"?> color and maybe that's why he's shedding. <Unlikely> Any help would be appreciated.. <Could be routine shedding, but I suspect it might be a reaction to environmental stressors.> Thanks so much <Welcome, Mich... squinting for free Internet service...>
Re: Toadstool coral... Natural Diversity   10/21/07 Hi <Hello again, Mich here.> Thanks for your advice earlier, <Welcome!> my toadstool is looking excellent now <Good to hear... Though I wish I was still squinting for free Internet in the Bahamas...> but I had one last question. <OK> My toadstool is a very large and mature one but when I look at other pictures of toadstools, they all have circular, perfectly round stalks. <Not always the case.> Mine is like a triangle. <Is fine.> He's doing great though. <Excellent.> Any explanation would be great thanks. <Is how it grew... likely a product of its environment.> He's the typical brown toadstool. Also when I look at other toadstools, when they close their whole crown goes in while mine only retracts its tentacles. <This is not unusual. Mich>

Leather Tree Coral Sick   9/28/07 I wrote about a week ago with a lighting issue in my 55G reef tank. I purchased a new ballast for my current satellite fixture and all of the corals look happier, except one. My leather tree coral is having troubles. First of all it went through a period of time where it was limp, still looked healthy but just limp. Well after changing the ballast it has straightened up but now it has what appear to be burns on the tips. The tips are white and when disturbed they disintegrate. It also seems exceptionally prone to injury. I picked it up to rinse it in a bucket of tank water, and just my hand cradling it ripped a big tear in the base. Is this coral experiencing too much light? I tend to think so but in researching the issue on your site I have found that typically bleached corals do not disintegrate or experience any kind of wasting. Also is its propensity to injury indicative of any larger issue? <Most likely yes. Was the coral dyed? Dyed leathers can be very sensitive to contact. It's also possible that there's something else in the tank that is toxic to the coral (this could be anything from another coral to something in an additive/supplement/food/decor/etc.). Just in case, you should start running activated carbon ASAP (also because the dying coral is also toxic). Leathers do shed periodically (and possibly prompted by stress). So if this dying tissue is actually just a layer over a lot of healthy tissue, then maybe it's just shedding (but it doesn't sound like it).> All of my parameters are normal. Ammonia/nitrites 0ppm, nitrates 10ppm, calcium 400ppm, ph 8.2, temp 80F, good flow, great skimmer. <This coral seems to be dying. It's difficult to say why without a lot more information (and even with all the information, we still might not know for sure). I don't think a lack of, too much, or even a sudden change in lighting alone would do this to a leather coral. The sudden change in lighting probably exacerbated some other problem the coral was having. If the coral is rapidly disintegrating, I would remove it from the tank. The dying tissue of these corals can spoil your water. I'm sorry to say, I'm not sure if the coral can be saved at this point. If it were my coral, I'd try to find the healthiest part and frag off the rest. Good luck, Sara M.>

Distressed Leather (Coral)? -- 09/22/07 Thank you so much for this website. It is very informative and has helped us out tremendously. <Glad to hear that. we have an amazing bunch of talented people that I'm honored to work with. Scott F. in today.> We have had a Toadstool Leather coral for about a month and it has been thriving. The last few days its polyps have not really come out and we noticed some small yellow patches on the top. We did accidentally hit it the other day when we were doing a water change. Do you think this is what it could be? It seems to be doing a bit better today (its polyps have all been out), but we want to make sure that this is not something to be concerned about. We do not want to threaten our other coral. Thanks, Bellinda <Well, Belinda, I have seen this before on my specimens. I am very clumsy when working in my aquarium, and I have knocked into my Fiji Yellow Toadstool Leathers a few times. They do develop what looks like a "bruise" like this if you whack them hard enough. An interesting reaction. In every case where I have seen this, the coral has recovered without further issues in just a few days. I'd keep a close eye on the coral, but if it's like mine, it should recover. In severe instances, if the tissue starts dying in the affected location, you can take a razor blade and cut away the necrotic tissue. Again, in clean water and good conditions, the coral should recover just fine. These guys are practically "bulletproof" if well cared for. In fact, they are so easy to care for and propagate that, one day, we may be able to supply all of the hobby demands for this species of coral through captive propagation, thus reducing pressure on the wild populations. Hope this helps! Regards, Scott F.>