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FAQs about Brown/Phaeophyte Algae/Kelp: Genus Dictyota

FAQs By Genus: Lobophora, Sargassum

Related Articles: Brown AlgaeAvoiding Algae Problems in Marine System, Algae Control, Marine Maintenance, Nutrient Control and Export, Marine Scavengers, Snails, Hermit Crabs, Mithrax/Emerald Green Crabs, Sea Urchins, Blennies, Algae Filters, Ctenochaetus/Bristle Mouth Tangs, Zebrasoma/Sailfin Tangs, Skimmers, Skimmer Selection, Marine Algae, Coralline Algae, Green Algae, Brown Algae, Blue-Green "Algae"/(Cyanobacteria)Diatoms, Brown Algae

Related FAQs: Brown Algae 1, Brown Algae 2, Brown Algae Identification, Brown Algae Behavior, Brown Algae Selection, Brown Algae Systems, Brown Algae Nutrition, Brown Algae Disease, Brown Algae Reproduction/Propagation, Marine Algicide Use, Nutrient Limitation, Marine Algae Eaters, Culturing Macro-Algae; Controlling: BGA/Cyano, Red/Encrusting Algae, Green Algae, Brown/Diatom Algae, Marine Algae ID 1, Marine Algae ID 2, Marine Algae Control FAQs II, Marine Algaecide Use, Nutrient Limitation, Marine Algae Eaters, Culturing Macro-Algae; Controlling: BGA/Cyano, Red/Encrusting Algae, Green Algae, Brown/Diatom Algae,



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Marine Aquarium Algae Control

by Robert (Bob) Fenner

Dictyota Algae - Rabbitfish      3/1/19
My tank is being taken over by this invasive plague. Researching online it seems this algae will be consumed by S. Doliatus, Two Barred or Scribbled Rabbitfish. The issue I am having is finding this fish. It seems everyone only brings in S. Virgatus and they look very similar. Do you think this fish will eat Dictyota?
<Likely to some extent; yes>
<Welcome. Bob Fenner>
Re: Dictyota Algae - Rabbitfish       4/18/19

Wanted to let you know I ended up getting a Gold Spotted Rabbitfish instead. It's been in QT and I have been feeding this fish the Dictyota from my display.
Literally devours it in seconds. I am a bit concerned though about the potential to eat coral. From my research and readings it seems like this specific fish tends to be a Zoanthid eater. Any experience around leather corals, clams, etc?
<Not usually a problem; problematical>
Is this fish really more prone to eating coral then some of the other rabbits?
<Not as far as I'm aware; no. Siganids aren't "coral" eaters period; they may nip; but rarely do much damage.>
<W. B>

Stopping the dreaded Dictyota in its tracks (nuisance macroalgae control>  9/1/08 Hello Crew, <Hey there! Scott F. in today!> I am having a problem with Dictyota algae in my 250g reef system. It is not that the algae is completely taking over - it is growing quite slowly due to my low levels of nutrients (nitrate and phosphate are zero, big refugium, powerful skimmer, DSB). <Oh, darn- a healthy, stable system! Seriously, though- consider yourself fortunate, as this can be one of the absolute nastiest macroalgae to deal with. Of course, if you're trying to grow the stuff, I can understand that you might be a bit frustrated!> My pH is quite high (8.4) (Kalkwasser dosing with pH-controller) day and night and I only seldom dose iodine or trace elements, I do an 8 to 10% water change every week. <Great husbandry!> It would not be a problem to siphon the algae out every once in a while. Some parts of the Dictyota do, however, stay attached to the surface of the live rock and sometimes these parts begin to crawl up on my corals' bases. <Yup- seen that before!> It has reached a point where I have to scrape off some coral tissue together with the algae to prevent the Dictyota from slowly crawling further up on my corals. <And so the invasion begins...PLEASE be very careful here. I have seen this algae literally take over some beautiful aquariums. Even the smallest fragments, as you are discovering, can form new aggregations, smothering sessile invertebrates in the process. I'm going to talk a bit about this species in one of my MACNA presentations in Atlanta next week. I'm not a fan of this algae!> Thus, I was thinking of adding a Siganus doliatus/virgatus or a Naso tang to my tank to help with removing the algae from the coral tissue. I know that both fish are said to be among the few to eat Dictyota, and I have read your articles and FAQs (besides reading the daily FAQs ;-) as well as other sources on Dictyota elimination. Due to the small size of my system I would prefer one of the Siganids, my only concern is that due to the noxious nature of this algal family they might not eat it. So my question would be what you would recommend in my case? Which would be the better route to go? And if the Siganids - which species? Thanks in advance & best regards, Alex <Well, Alex- you asked...I am a bit skeptical about these fishes feeding on Dictyota. I have not seen a situation personally in which these fish-or any others-dine on this stuff with any degree of regularity. Sure, a specimen may develop a taste for the stuff, but I'd think that to be the exception rather than the rule. As you surmised, Dictyota is not particularly palatable to fishes. I am also not a big fan of the Siganidae. However, if I had to try one, I'd go for the so-called "One-Spot Foxface" (Siganus unimaculatus), which is about the smallest member of the family regularly available to the trade, topping off at about 8 inches. It's still a big, clumsy, aggressive, skittish, relentlessly active fish, IMO. It is known for producing copious amounts of organic waste, and is also capable of causing damage to corals and clams because of it's relentless grazing habits (gee-can you tell I'm NOT a fan!). Oh, yeah- I forgot to mention that it also possesses venomous spines, creating a potential threat to the hobbyist. All in all, I'd recommend keeping your Dictyota in check by either manual extraction (best accomplished by removing the affected rock/coral from the aquarium and removing the algae in a separate container of tank water. Yes, it's tedious, but I feel it's the most efficient, reliable way. However, please don't take my word and personal experience as the gospel. I have heard other hobbyists claim that the fish can help. If you like the fish, and can accommodate it and it's behaviors- go for it. However, if that is a potential problem, I'd continue with the tedious but effective practice of manual extraction. Hope this helps a bit. Good luck in your battle! Regards, Scott F.>

Re: Dictyota - Rabbitfish or Naso? Dictyota- The Algae from Hell (Cont'd)  9/10/08 Hello Scott, <Hello again!> thank you for your answer & wishes - so the prospectus of getting rid of the algae is not very good... I had already read numerous scientific articles regarding the vast array of herbivore deterring secondary metabolites of this genus but had hoped that there was some animal liking the stuff (or at least eating it with disgust - I wouldn't mind). But it seems that in this case the cure could be worse than the disease - if that is possible. <Oh, it can be...> Best regards to all of you & keep up the good work, Alex <As an interesting side note: After my MACNA talk on algae last week, an attendee shared that he utilized a Scopas Tang (Zebrasoma scopas) to eat this stuff! Go figure...and ugly Tang with a beautiful appetite! Good luck! Regards, Scott F.>

Dictyota: Nasty Nuisance or Attractive Algae?  -- 05/07/07 Hey WWM, <Hi there! Scott F. with you tonight!> First off I want to thank all of you for all the knowledge posted on this site. It's been literally a life saver for a lot of the contents in my tank. <We're thrilled to bring it to you each and every day...We really have some special volunteers here who do a remarkable job!> I've got a couple questions for you all about some algae (from what I've seen and read) it's scientific name is Dictyota dichotoma from what I've found around the web. I'm wondering how this stuff affects the rest of my tank. I have it placed in the upper middle part of my tank, sitting on top of a large chunk of live rock. The photo is attached. <Unfortunately, I could not open your pic, but suffice it to say, I do have some pretty strong opinions on Dictyota! Although it is quite attractive, and grows relatively quickly, it can become a horrific nuisance if left unchecked, IMO. It can grow over large tracts of open space in your tank, potentially smothering sessile inverts and other macroalgae. If you want this stuff, do carefully "prune" it to keep it contained to the area in which you want it. One warning, however: even the smallest fragment of this algae, if left in the tank, can drift to a new location and take hold. I've literally seen aquariums taken over by the stuff. My best advice for pruning it: Remove the rock on which it resides, and pull off the unwanted fragments outside of the aquarium. Swish the rock carefully in a bucket of system water to wash away all of the remaining fragments, and then replace the rock. Not trying to spook you about this algae, but you need to be aware of its potentially explosive growth potential, If you do want it, Dictyota is a very attractive algae.> I also wanted to just check and make sure that my setup will do the job for what I have, since I'm writing you. I've got a 95 gallon tank, my pump circulates the water about 10 times per hour (900 gph). The pump is in a sump which I plan on converting to a refugium. I also have my protein skimmer mounted on the refugium with a custom made acrylic cover over. I've got some Red Gracilaria and some Chaetomorpha coming in soon as well. <All sounds in order!> I've got two hood lamps, one is fluorescent 50/50 (6,000k, actinic 03). The other lamp(s) are as follows; two 65w actinic, one 7,200k, one 10,000k, and a strip of LED moonlights. All lights on the second hood are power compact except the LED Moonlights. The power compact hood has  legs that prop it up about 6" from the top of the water level. The glass cover over the tank is about 1"-1.5" above the water line. <Sounds nice for many of the less light-demanding photosynthetic creatures we keep in our systems. I have always liked compact fluorescents for the wonderful aesthetics I think that they bring> This is what's in my tank.... 100 lbs of Tonga Live Rock Chile Coral Elegance Coral (which just recently died I came across this web site  trying to save it, it was about volley ball size, a real bummer) <A tough coral to "save"...has some specific requirements which you'll want to meet. Do research here on WWM and other sources for the needs of this coral.> Mushroom Rock Assorted Polyps (about 7 small) Two Yellow Tail Damsels Twin Spot Lionfish Six Line Wrasse Flower Anemone 3 Hermit Crabs Coral Banded Shrimp Red Flagweed White Sponge (covers the rock with the mushrooms on it) There's also a few sponges that I can't identify <All part of the fun in keeping a reef system.> Any advice on my set up would greatly be appreciated. This site has helped me tremendously and being able to send in a question makes it that much better <I am a firm believer in regular, frequent water changes (like 10% weekly, or even two 5% water changes per week.> Oh and one last thing. I left my Elegance Coral's skeleton in my tank, I'm considering filling it with polyps or mushrooms will there be any problems with that? <If the coral died, as the tissue decomposes, it can seriously degrade water quality. Be sure to remove it and keep up on regular maintenance and keep your protein skimmer working. Once you remove and clean the skeleton, it can certainly be used in the future as a substrate to mount your other corals on.> Thanks all!
<My pleasure, Matt! Regards, Scott F.>

Dictyota control and Rabbitfish  - 05/02/07 I am a loyal reader of the WWM site, and have gained a tremendous amount of expert advice and guidance, paying no more than a couple of mouse clicks and some key strokes. For that reason, I feel obligated to share something that I have come across, hoping to give a small piece back to the WWM community. <I/we thank you> I have a 125 Gallon reef tank, with 2 bubble tip anemones (was one, split a few months back), 1 large branching Acropora , 1 large Montipora , 1 orange plate coral, 1 green open brain, 1 clam, several branches of frogspawn, and other assorted small corals.  Also swimming are 2 Solomon Island Black Perculas , 1 royal Gramma , 1 Kole Tang, and 2 clown gobys. About 6 months ago, I started to get an algae bloom of what I would later learn was the dreaded Dictyota .  Unaware of its nature, I tried to remove the Dictyota , but this only made things worse, spreading like wildfire around the tank.  I was removing tons of it every week, but I was only managing to keep it short, it was covering about 2/3 of the visible rock in the tank.  I only managed to keep corals from being choked out by siphoning off chunks of the Dictyota that surrounded each one 2X a week. I did my research on line, where urchins, diadema , and sea hares were all rumored to eat the stuff'¦.they didn't.  The owner of my LFS said that he knew no way of ridding the tank, short of a 2 month lights out period (that would not be so good for the corals). Naso tangs were also rumored to eat the Dictyota, and in fact on ate some at the store so I brought him home.  He started to eat the stuff, but then after one day, refused to eat anymore, and he died a couple of weeks later.  If seemed to me that he may have died from eating the algae, which I hear can be noxious. Not wanting to kill another fish, I decided on a last resort, something I had seen written somewhere obliquely on a posting.  I bought a two-barred Rabbitfish .  He didn't eat anything for the first two days in the tank.  On day three, I saw him nibbling a little on the algae.  Over the next three weeks, I saw him actively swimming, and nipping only once in while.   Yet his belly seemed full, near bursting.  It has now been only a month, and the Dictyota is all but completely gone.  I cannot believe I have my tank back.  I still am in shock that 8 months worth of frustration is over.  It seems impossible to me that this tiny wonder of about 3 inches ate what must of amounted to 8 lbs of algae or more. With the algae gone (hopefully never to return), I now have a hero of a fish, who instead of dining on Dictyota , will enjoy a life of Nori , greens, herbivore preparations, and protein. I am not sure if you have a forum for this, <Oh yes... both for Rabbitfish Selection and Brown Macrophyte control> but please share this with your readers.  Searches for info on the subject brought about frustratingly pessimistic analyses.  I want to let people know that Dictyota can be defeated, and all it takes is a three inch lawnmower called the two-barred Rabbitfish .   Brant Goldsmith <Thank you for sharing. Bob Fenner>

Dealing With Dictyota - 04/27/07 Hi Crew, <<Hello Tim>>    Thanks for taking my e-mail today! <<Quite welcome>> I have a primarily SPS reef tank that has been pretty successful for almost three years now.  However, in the past few months I have experienced problems with my AquaC Remora Pro protein skimmer.  I am sending it to the manufacturer to get fixed. <<Ah, very good...Jason Kim is a great guy and will take good care of/will treat you right>> Since the problems, I have experienced a slow but steady outbreak of brown algae (Dictyota sp. as ID from your website). <<This alga requires iodine...if you are dosing iodine; the removal of the skimmer may be allowing a sufficient surplus now to feed the Dictyota>> It should also be noted that I have a refugium with Chaetomorpha spp algae to export nutrients. <<Excellent...am a BIG fan of vegetable refugiums>> Once I get my nutrient export (protein skimmer) in control I want to try and combat this alga (I do 20 percent water changes weekly so I don't think it will take too long). <<Maybe so>> It grows in a relatively low lying morphology and is rather hard to crop. <<Isn't that always the case? [grin]>> Is there a species of snail, hermit, fish, etc. that has a taste for this brown algae? <<A Naso Tang is a good choice, if your system is large enough...else you might try a Salarias or Atrosalarias blenny species>> I haven't seen anything this specific on your site. <<Hmmm...I'm pretty sure both of these are mentioned somewhere...maybe for a different species of brown alga>> My goal is to crop out as much as I can by hand and then let the rest slowly die off from predation and lack of nutrients (when the skimmer is fixed). <<Sounds like a plan>> Thanks for the help! Tim

Dictyota Algae Control 1/23/07 Crew, <Jeff> I've been struggling with Dictyota in a 29 gallon for a while. It has invaded every inch of the tank - as I mistakenly allowed it to spread before I realized how invasive it is - and outcompetes my zoanthids unless I dedicate a substantial amount of time to manual extraction. I've been toying with the idea of adding a long-spined urchin. Is a 29 gallon (with roughly 30 lbs. of live rock and a 1/2" sand bed) too small for a small long-spined urchin? If not, how long could I house the urchin in the tank before it outgrew it? I'm pretty confident I will have room for a large tank in 2-3 years. Thanks for all your help and the website. <Jeff, rapid growth of this specie of algae usually indicates a high nutrient level in the water.  When nutrient levels are low, they can be out-competed by other species of algae (Caulerpa, etc) more suited to a lesser nutrient content in the system.  It may be difficult to find an animal that eats this specie of algae as they contain some very potent anti-predation chemicals.  I don't believe an urchin will help you here as most graze on hair algae.  Do read here and linked files above for more help on eliminating this algae by means of nutrient control. http://www.wetwebmedia.com/nutrientcontrol.htm I'd consider a small hang-on refugium to propagate Caulerpa algae.  James (Salty Dog)>   -Jeff
Re:  Dictyota Algae Control 1/23/07
Thanks, James. <Welcome.> I will light my refugium - running just for pods with a DSB at the moment - as you suggest. Out of curiosity, would the 29 gallon tank be too small for the long-spined urchin? How long might it fit comfortably? I am generally interested in this species as an aquarium resident. The Dictyota consumption was an ancillary benefit suggested by one of Anthony's posts. <You can keep the urchin in a 29.  I'd try and get a small specimen as they can get rather large in time.> Thanks. <You're welcome.  James (Salty Dog)> -Jeff

Algae killing my corals   5/26/06 Hello, I'm moving in a few days and will be tearing down & reassembling the tank. Right now I have time to do what will be necessary to kill/remove these algae (if possible). This is what it looks like: http://www.botany.ubc.ca/people/rob/plate4.html (pictures b & c). <Mmm, looks like some sort of Dictyota species...> This algae hitch hiked on my Walt Smith Fiji live rock from 1 1/2 years ago. I have been trying to keep it in check by weekly plucking. however, when I pluck, a few errant leaves drift about and reattach to anything they land on including corals (even the fleshy parts), sea cucumber, sand & shells ( I guess that's everything except the fish). Attempts to further pluck always leaves a small portion attached that re-grows even when I use a course bristle brush. It is slowly taking over my tank and becoming impossible to remove from corals because the method of removal will kill the polyps or scar the affected creature. This coral grows best under high water flow but will grow anywhere there is light. The only thing helping the situation is my urchin who scrapes the rock clean where ever he passes but he only comes out at night so his aid is minimal and so far I've found nothing else that has an appetite for this plant. I don't know what to do. Each weeding session is taking longer and becoming less effective. All other aspects of my reef keeping have been successful and all the water quality tests are outstanding. I'm at a loss; I hope you can help me. Joshua Mansinon <Do you have room for a Naso species Tang? This is my first choice in control organisms for Phaeophytes as this. Bob Fenner>

Re: Algae killing my corals (attn Bob Fenner) I swear I'm not doing it!   5/27/06 Bob Thank you for the quick response. Unfortunately I don't have the room for a Naso Tang, my tank is only 40g so size is a factor. Do you know of any other creature that can help? <Mmm... well, there are a number of mainly other fishes and gastropods that do... but of animals that are readily available in the trade to try... perhaps a Salarias or Atrosalarias blenny, Mithraculus crab, even a Yellow Tang (Zebrasoma flavescens)...> Is there any thing that I should try while the tank is broken down? Any little tip would help, I'll try them all. Thanks Joshua Mansinon <Favoring other macroalgae species (greens and reds) (Culturing them in a lighted, tied-in sump/refugium) and stopping the dosing of iodine/ide/ate compounds (brown kelp/algae need) will likely limit this Dictyota overpopulation. Bob Fenner>

Urchin saves the day - eating Dictyota 2/2/04 Hello again Anthony, I wanted to give you an update about our Dictyota problem. Our urchin is now eating it. :) <outstanding to hear. I do love those urchins> We could not be more happy to see the right upper half of the tank free from this plague. Slowly the little urchin is going to town on it. Mark took a picture of the urchin to the SeaBay meeting but he never got the chance to show it to you. <Awww... no worries. DO send it here if you like> We are now sure it must be a long spined urchin. I hope he keeps up eating the Dictyota. If it eats all of micro algae will it be happy to eat any coralline algae? We don't want it to starve. <hmmm... tough to say. If so, I don't think it will survive on it. Fortunately, they will scavenge food bits. Offer an algae based frozen food and likely it will be fine (2-3 times weekly) after the nuisance algae is gone> Sincerely, Clair & Mark Dawson <best regards, my friends. Anthony>

Nuisance Dictyota Algae 1/7/03  Anthony- I hope it is OK to write to you here. Amy told me it would be better to write to this address with my question. If I messed up I do apologize.  <no worries my friend... very welcome to e-mail here or any addy I have (readingtrees.com , yahoo.com, etc). Its nice here though as answers can be shared/archived for the benefit of others. Very sorry for the delay by the way... I left for the Colorado Rockies on Friday when you e-mailed and just got back>  I have a question about a Dictyota problem we are having.  <Arghhh! Can be pretty to look at, but becomes a nuisance>  Some back round about my tank as follows: 125 gallon, 2X250 watt radium's. Euro-reef skimmer and a 45 gallon refugium. Ammonia nitrite nitrate all test zero and our ph is 8.2 during the day 8.0 at night. Alk 11dkh and CA 375. We keep the temp at 81 degrees. A 4" DSB and 140 pounds of live rock.  We have a mixed reef that I know you will not like to hear about. Sorry about that.  <heehee... no worries. Just try to focus/group better animals (more natural/biotopic or akin/"amiable" species) when possible>  We get preached about it all of time but I am not going to change it no matter what my husband or Amy tells me. Sorry. You can chew me out if we meet soon.  <you are safe :) >  About the Dictyota. It has spread all over the rocks. We pull it out daily and mess with the skimmer so that we can get a least 1/2 cup of dark stuff each day. We have tried every animal we can think of to eat this and nothing has.  <indeed... it can be highly invasive, is noxious and not readily controlled by herbivores>  A Longspined urchin was put in two weeks ago with the hope of it eating the Dictyota but it only eats the coralline. Do you have any suggestions?  <hmmm... odd. Diadema urchins are one of the few that are likely to control it. They are also one of the least likely urchins to eat coralline. De send a pic or recheck the ID of your urchin. I wonder if its a Diadema?>  We are afraid for our LPS after reading about this algae in your new book.  <being an educated consumer gives you the freedom to shop anywhere... including the less knowledgeable places. Great stuff to be found even there (and often so) as long as you have done your homework. Don't give up on that LFS just yet :) >  Thank you for any advice you can give. I hope my husband and I can meet you at the SeaBay club this month. Kindly Clair  <outstanding!... be seeing you soon :) Anthony> 
Nuisance Dictyota Algae 1/8/03
Anthony- Thank you for the reply. I am going to look on-line and in my RI book to make sure I have a long spined urchin. I'm pretty sure we do but I will check to be safe. <yes... all good. Or do send us a small digital pic :) > I think you might have misunderstood me in my last e-mail. I am not worried about my local fish store, I was worried about my LPS (large polyp stonies). <Ahhh... yes. My fault dear, I read too fast and see now <G>> I am sure I remember reading that Dictyota will harm them if the algae grows on the skeleton. <very very true. Its quite a nuisance> I have two bubble corals and a frogspawn that has the Dictyota on it. My husband has been pulling it off weekly but it is upsetting the frogspawn. We are not sure if the algae is upsetting it or having the algae pulled of it so often. <other than nutrient control to starve it out, and help from diadema... there is little else besides manual extraction. This is just the sort of "harmless" organism that needs to be screened in a quarantine tank when all new corals, rocks, plants, etc are brought in> We will let you know what we find out about the urchin.  Kindly, Clair <best regards my friend... see you soon! Anthony>

Dictyota Hi Crew <Joe> I am at the verge of tossing all my live rock in the trash. I have had a Dictyota outbreak in my 90 gal for a while now. I bought a small Naso that wiped it out but as we know the Naso was too big and now resides in a 200 gal. I have an ev120 skimmer and a 30 gal sump with macros growing. I do 10/15 gal water changes weekly with 0 TDS. I don't know what to do. <Re?> Joe Culler, <You could kill off this brown algae by placing your LR in the dark for a few weeks... Bob Fenner>

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Marine Aquarium Algae Control

by Robert (Bob) Fenner

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