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FAQs about Sea Slugs, the Opisthobranchs, Compatibility, Dangers, Removal 

Related Articles: Sea Slugs, Nudibranchs,

Related FAQs: Seaslugs 1, Seaslugs 2, & FAQs on: Seaslug Identification, Seaslug Behavior, Seaslug Selection, Seaslug Systems, Seaslug Feeding, Seaslug Disease, Seaslug Reproduction, & Marine Snails 1Marine Snails 2Marine Snails 3 Nudibranchs, Nudibranchs 2, Nudibranch Identification, Nudibranch Behavior, Nudibranch Compatibility, Nudibranch Selection, Nudibranch Systems, Nudibranch Feeding, Nudibranch Disease, Nudibranch Reproduction, Berghia Nudibranchs, Snail ID 1, Snail ID 2, Snail ID 3

Let's see... slow to very slow moving, many are very distinctive... reverse-camouflaged actually... Warning colored! Oh yes... not palatable to outright toxic!


Nudibranch ID; other      1/23/16
Hello. I've attached a pic of a hitch hiker
<A nice one too!>
I just discovered with a flashlight at night while feeding my corals. It appears to be some sort of yellow Nudibranch.
<Mmm; not to me; this looks more like a Sacoglossan...
It stretches out to about an inch long. I have it housed in a separate container for now. Do you have any idea which
species it is?
<Some guesses. See WWM re the group>
And do you think I should remove it from my tank?
<Mmm; likely not harmful... most shelled and shell-less members of this group of Seaslugs are algae eaters>
It's an SPS dominated tank.
Thanks for your assistance!
<Thank you for sharing. Bob Fenner>

Lettuce Nudibranch; stkg., comp.       9/16/15
WetWeb crew,
First thanks fir reading my email. I just recently starting adding lettuce Nudibranchs to my 75 reef. Added the 2nd one after I lost the 1st one.
<These/Elysia; do "just die/dissolve" mysteriously>
I check levels daily. So I think I can rule out water quality, but after a few days they just have "disappeared". My tank consists of 1 yellow tangs, 3 green Chromis, Ocellaris clown and purple Firefish. I have a typical cleanup crew, snails and herm. Crabs, but have a territorial coral banded shrimp. Is this potentially my culprits?
<Oh yes; most prominently the Stenopus; but depending on the species, their hunger, Hermits can be/come opportunistic as well. I would not stock Sea Slugs here>
Any information you could help with would be great. Thanks again! Sincerely,
Bryan Varone
<Thank you for writing/sharing. Bob Fenner>

Lettuce Nudibranch Compatibility 11/2/2009
Hello all, thanks as always for the excellent info and site.
I found this guy at my LFS, I think he is a Lettuce Nudibranch (*Elysia crispata)*. My understanding is that they are hair-algae eaters.
That being said, I have a moderate amount of hair algae on the back of my tank, are there specific types they eat, or are all hair algae equal for dietary purposes?
<Ah I think they will likely take care of most of the green hair algae.>
Also, I have a damsel, fire goby, and fire shrimp.
Nothing that should eat a Elysia correct? I would like to acquire this specimen if it is reasonable.
<I don't think it will be a problem compatibility wise.>
<Good luck, Josh Solomon.>

Seahare comp., fdg. Hi Bob Another new question for you......Does a Sea Hare care what it has in its mouth? <Mmmm> That may sound really stupid but I have a Zoanthus colony with a very fine hair algae (green, massively invasive) encroaching and I believe smothering. If the Sea Hare chooses to eat the algae, will it also eat the polyps in the same mouthful? <I do think Aplysiids care... and Zoanthids are very toxic... Do read here: http://wetwebmedia.com/seaslugsopisthobranchs.htm and the linked files above... many Seahares are misplaced in aquariums... and elsewhere on WWM re Zoanthid comp.> Best wishes as always Sarah <RMF>

Re: Infected Tank??? Aplysiid sel.   4/1/08 Hi Bob, <Cynne> Hope this finds you well. Once again I have encountered a question regarding stock. The tank is the same as I described before. I now have 90 % of the Scorpions on frozen food, as well; I have followed your advice and purchased the Aqua C Remora Protein Skimmer with Mag 3 pump. I also have increased to a 4-6 inch sandbed with some aragonite. The Scorpions are so much fun :) I cannot believe that I enjoy them even more than the seahorses. <Both have/exhibit interesting behavior for sure> I no longer have the starfish; I sacrificed him about 2 months ago for a CopperSafe ich treatment (entire tank). I had to choose between the $17.00 starfish or the $1000.00 fish. I have since changed all filter media, changed 100% of the water in 25% intervals over a couple of weeks and rebuilt the biological with rock rubble from the LFS. I also continue to run poly filters and charcoal in the Aqua Clear. My question is I recently purchased a sea hare. I have always wanted one, but was afraid of inking. <Mmm, not an issue with many... tropical species. Unfortunately there is a current rush of selling large, non-tropicals...> I have searched your site but am still unsure as to what I have. According to one of Anthony's replies, I found that any Sea Hare with tassels is Carnivorous? <Mmm, no... not a sure characteristic> The pet store said this one was a Herbivore and they weren't sure regarding toxins. I also found one currently running on EBay and according to the seller; this guy isn't toxic http://cgi.ebay.com/NANO-Hairy-Sea-Hare-Reef-Aquarium-Live-HAIR-ALGAE_ W0QQitemZ290207618335QQihZ019QQcategoryZ66788QQrdZ1QQssPageNameZWD1VQQ_ trksidZp1638.m118.l1247QQcmdZViewItem. They also advertise this as a Nano size, Yet he looks a lot like the one on your FAQS page 2nd photo. <Mmmm... is this Bursatella leachii? Am thinking so... get's a bit large for nanos, but is tropical...> I bought him in NC, I am desperately hoping he is not a cold water species. He is fat bodied brown to green in color with black splotches. He also has baby blue specks all over the body and head, as if someone splashed paint on him, and he is tasseled. Please help I can get whatever food he needs. I just need to know what to expect. The fish do not mess with him at all and all intakes on filters and power heads are covered. Thanks again for all your advice!! You guys are great!! Cynne <Do see the Net (Google images et al.) for pix, ID... BobF out in Borneo>

Sea Hare/Systems 2/28/08 Hi <Hello> I was thinking of purchasing a sea hare, however I am a little concerned with the fact they produce poisonous ink. If none of the other fish provoke it could it still ink? <Possibly, and can release the ink upon their death.> What would happen if it was to die would the ink be released? <Could lead to the death of other inhabitants. I very good chemical filter is needed to remove this compound if released.> I have a 180 gallon reef tank with a Clown Fish, Yellow Tang, Hawk Fish, Sleeper Goby, blenny, and various corals and a few different kinds of shrimp. Would this be a good set up for a sea hare? I have an abundance of algae. <Adam, these animals are very difficult to maintain and I would discourage you from getting one. It will eventually die and cause problems for you.> Thanks, <You're welcome. James (Salty Dog)> Adam

Aiptasia & Sea Hare comp.... & Bio. alg. contr.    2/3/08 Although our 55 gallon FOWLR has been doing fine (fish growing & happy, no death, stable water) I have three nickel sized Aiptasia and some hair algae. Can/will the sting of an Aiptasia injury or kill a Sea Hare? <Won't be the best combination but certainly not the best solution for both problems. For the Aips see here: http://www.wetwebmedia.com/marine/inverts/cnidaria/anthozoa/aiptasia/aiptasia.htm. And the causes of the Hair Algae must be addressed first. The Sea Hare will just be recycling the nutrients the algae use. Read on Nutrient export etc. Olly>

Sea Hare (Aplysia dactylomela) And 'Ink Scares' In A Take-All Battle Against Hair Algae! -- 01/28/08 Thanks for the great site; it's really helped me understand my reef aquarium. <<A collective effort 'we're pleased you have found it of use>> I have a 55 gallon reef setup with a Major Hair Algae problem. <<I trust you have perused our articles/FAQs re'¦>> I've had the setup for about 2 years and since getting some new corals, mushrooms, and additional pieces of live rock 6 months ago, hair algae has begun to take over and I'm considering desperate measures to get rid of it. <<Mmm'¦if the pest alga was not a problem before, obviously one or all of the additions have upset the 'balance' of your system. Perhaps your filtration methodology is now insufficient for the bio-load. Or perhaps the new rock introduced a contaminant (Phosphate). All speculation at this point, I must admit>> *Background info: My nitrates, phosphates are continuously at zero. <<Likely not 'just consumed by the algae/corals faster than can be detected>> Perform bi-monthly water changes at 10%. <<Monthly changes of 20% might be called for/of use here>> I reduced lighting from 12 hours to 8 hours (but now my BTA and corals don't seem as full or bright). <<Indeed 'Others may, but I never recommend reducing the lighting photo-period just to battle nuisance alga>> *Livestock: Mated pair Maroon Gold Striped with BTA, Lawnmower blenny, yellow Tang, random soft leather corals, 2 open brains, one large closed brain, green bubble coral, green torch long tentacle coral. <Quite the 'reef garden' eh>> Inverts: 15 Turbo Snails, 15 Nassarius snails, 10 Nerite Snails, 3 Emerald crabs, 20+ hermit crabs (blue & white legged), Sand sifting cucumber, Caulerpa and Macro algae. <<Caulerpa 'is' a species of Macro Algae 'and mixing species of macro algae can be as problematical as mixing corals re fighting for space, allelopathy, et al>> *Hardware: Lighting: T-5 HO: 2 Actinic, 2 10,000k; Protein Skimmer, <<Might also be time for a bigger/better skimmer>> 2 powerheads, <<More 'flow' will also be of help re the nuisance algae, and coral health in general>> Filter, <<This will be a large source of your problems if not attended/cleaned 'at least' once a week to prevent buildup of decaying organic material. And if you're not already, consider adding some chemical filtration (carbon/Poly-Filter)>> with No sump, temp kept at 76F. Now after taking some rocks out and manually pulling out hair algae they've started to grow back!! Grrr! <<Indeed'¦ You need to find/address the 'source' of the nuisance algae>> It is completely overrunning my blue and purple mushroom patches and I don't know what to do... <<I've listed a few avenues of investigation>> I'm considering adding a Spotted Sea Hare (Aplysia dactylomela) or similar one available after seeing before and after photos of them eating hair algae. <<Can be quite efficacious re, but is not a panacea. You will still need to address the source of your nuisance algae issue>> My issue: I'm away for a day or so and can't monitor my tank in case of an INK issue with the Sea Hare. Will the Ink kill my livestock if I can't do an immediate water change? <<The 'Ink' may well prove fatal in small closed-systems, but this will not likely be an issue. Unless attacked (I don't see any problems with your current stocking list), these animals are quite content to just roam the tank and graze. I have kept several of these fascinating creatures over the years and have never experienced any problems with 'inking'>> Are there any other non-toxic sea hares or animals I can add to get rid of the hair algae? <<Aplysia species are the most efficient at this that I am aware 'though these will also vary among individuals in their 'effectiveness'>> Could you please provide other reef suggestions to solve this problem? <<I have made a few 'but finding the 'source' is key here>> Thanks for your help. *Please email me your response or notification that you've responded. <<We always do>> I'll be anxiously waiting... <<Do read/re-read on our site re nuisance algae, its sources and methods of control. Start here (http://www.wetwebmedia.com/avoidingalgaeproblesm.htm ) and follow the associated links at the top of the page>> Thanks! <<Cheers, EricR>>

Re: Sea Hare (Aplysia dactylomela) And "Ink Scares" In A Take-All Battle Against Hair Algae! -- 01/30/08 Thanks for the reply! <<Very welcome!>> Follow up question: My fish guy says the Sea Hare may eat red algae and he's not sure about it eating Coralline growth on live rock. Does it eat Coralline? <<This has never been a problem in my experience 'these creatures generally feed on 'filamentous' algae>> I've attached some pics of my algae infestation. <<Yes, I see 'not so bad as some I've witnessed, and even experienced myself. I must also make mention 'that lovely Sea Apple you have is of more concern/poses a greater risk of poisoning your system than any inking issue with the Sea Hare>> Thanks a lot guys! <<Great gals here too'¦ Happy to help, EricR>>

Re: Sudden Appearance of a Bright-Pink, Flat Anemone! Seaslug/Hare comp.  3/6/07 Hi Bob <Angela> It has disappeared now and I will probably not see it again for another 2 months.   <?> I have looked at some pictures of button polyps and other Zoanthids, but mine only had approximately four or five little stubs around the outside of its 'face' and then another 4 or 5 a bit further in to the centre, and they were very short, and pointing out from the centre not upwards.  I am planning on getting a digital camera soon and so may catch an image in the future. <Good> When you said "do investigate the biology of this animal."  Did you mean the sea hare? <Yes> I have looked into it.  The store said it was Dolabella auricularia <The most commonly offered species> and from the pictures I have seen on the internet I believe this to be true.  I got it to eat all of my hair algae.  Now that all of the hair algae is under control I feed it dry seaweed everyday.  Do you agree with this level of care? <Mmmm> I have read that they can produce ink if threatened and that this isn't toxic, it just acts as a smoke screen. <Not so> Is there anything else I should know about it other than what I have found on your site?  (paranoid). <Do keep your eye on this animal, indeed all your livestock... as usual> Regarding the pink, possible Zoanthid; if it is one of these could it be a danger? <By itself? Unlikely> I have nightmares that I will come down in the morning and it will have swollen up to a foot across and eaten all my fish!! <Heeeee! Sorry... not probable> Thanks again Angela PS:  As sad as it is no I have not got one single Reefing friend...... <Mmm, unusual... perhaps a wider search, appeal on the Net... BobF>

Dolabella auricularia eviscerated?  Shrimp comp. 2/1/07 Howdy! <Hi there> I need some help with my Dolabella. <A Sea Hare, Aplysiid for you browsers: http://www.seaslugforum.net/factsheet.cfm?base=dolaauri>   Although I have spent a good part of this day searching the web, I can't seem to find any info to help me.  I have only had my Dolabella for a few weeks.  As you can see by the picture, the Dolabella seems to be having a problem at it's upper/inhalant siphon.  I think this is the cause of one very nosy cleaner shrimp.   <Maybe. What species? A Stenopid? I hope not> Whenever the Dolabella goes to clean the side of the tank where the shrimp resides, the shrimp hops onto it's back and goes to town picking the dolabella's *ahem* rear entry.  I have watched this many times, and as far as I could tell, the Dolabella didn't seem too annoyed and usually closes it's siphons and hurries away.  However, today I found my poor hare in protective mode, and seems to have either eviscerated or the cleaner shrimp has gone way too far and hurt it.  I know that it is still alive, and for it's safety, I have moved it to the other side of the tank away from the shrimp. <I would move it out period, and pronto... if it does eviscerate... this could be very big trouble for your system> I have inverted a plastic strawberry container over it to give it sort of an in-house quarantine.  It is not crawling or really moving at all.    <Move it> Here is the picture of my Dolabella.  Please excuse the arrows, I promise I am not trying to insult your intelligence! <No worries... Precious little there to insult... thankfully with concurrently small ego> I am going to post my experience/problem in another forum and I didn't want people asking which end was which.  lol <I see... and agree> Will my hare recover/survive?   <If given "good conditions" very likely so... Aplysiids are tough animals by and large... and subjected to all sorts of insults...> Is there anything I can do to help it further?  I am hoping the prognosis is favorable.  We have really enjoyed watching this creature. Thank you so much for your time and knowledge, I really appreciate it. I have learned so much here at WWM and it has helped me make many sound decisions.   Thanks again and take care, Karen Parameters: 75g w/ 20g sump CA  420ppm No3  0 No2  0 Ammonia  0 Phos  0 Alk  1.8 mEq/l (am working to bring it up) pH  8.1 salinity  35ppt <Mmm, well, "something" has to go ultimately... the Shrimp in question or your Hare... Bob Fenner>

Re: Dolabella auricularia eviscerated?    2/2/07 Dear Mr. Fenner, <Just Bob, please> I apologize for not giving the species on the shrimp, I meant to include it, but apparently forgot.  The shrimp is a skunk, Lysmata amboinensis. <Mmm, these are usually quite passive> Sadly, I discovered while transferring the hare to QT that it didn't make it.  I am very disappointed that I will not get to see it recover.  On a better note, my tank seems unaffected.  I did add a bag of fresh carbon just in case there are toxins. <Very good> Is there recommend any reading on these creatures pertaining specifically to husbandry? <Not as far as I'm aware in the popular literature... I have a bit of experience with the common S. Cal. Aplysia californica> It seems that there is surprisingly little information about keeping them in the home aquarium.   <Yes... though I strongly suspect that this and many other sea slugs/Opisthobranchs are going to be part of the near future "reef" experience... Some are very interesting, beautiful... and not difficult to culture> Although I would like to find more reading,  I will not attempt to keep one again until I can be sure that it can live in peace. I am very grateful for this site and the help.  I will, of course, help support WWM. Thank you.
<Life to you my friend. Bob Fenner>

Reef safe Nudibranchs   12/18/06 Hello: Another question for the experts as I seem to get conflicting results from my many www searches and the LFS staff. Are there any Nano-reef safe small-size sea slugs ? <Mmm, yes... many Opisthobranchs that could be utilized... depending on your other livestock...> I have a 3 month old 24G Nanocube which is doing well and don't want to repeat earlier mistakes. The information on Nudibranchs seems to vary and this in itself tells me to proceed with caution. <Mmm, yes... by and large I would not use Nudibranchs... look to, read re other Opistos...> I have seen "lettuce" sea slugs in my LFS's, as well as other more colourful species with a "Ricordea-like" texture on top. Thanks for the help, have been somewhat concerned about the number of species in the marine aquarium trade that really shouldn't be sold to hobbyists.....thanks again. Karl <Mmm, please see here: http://www.wetwebmedia.com/seaslugsopisthobranchs.htm and use the names presented as a starting point in searching further re this question. Bob Fenner>

Sea hare sel., comp.  12/30/06 OK, so after moving my tank (150g Berlin, 250lbs live rock, light bio-load) I had a huge outbreak of long green hair algae. Covered everything. Tried cutting back on the light, but I only achieved making it's color less attractive. After reading all I could, I decided I didn't want to go with scraping, chemical, etc....but add a natural solution. When weighing out the pro's & con's of such grazers, I settled on a sea hare, <Mmm, what species?> as it seemed to be the most voracious grazer. I wasn't so worried about it dying, as my tank is quite healthy and there is much for it to eat....... but with such a nocturnal creature, how on earth would you know if something that you rarely (if ever, lately...) see? <Mmm, the results of their night-time foraging?> Also, in a 150g, how much pollution/death could I be facing if I do not find the body? <Could be appreciable depending on the species, size... your filtration, maintenance...> 250lbs of rock is a pretty sizable pile to dig through. Thanks in advance, my briny friends!   -Pat <Do take care to try a tropical species (not a cool/coldwater one), that is, and stays small-ish. You have read here?: http://www.wetwebmedia.com/algaeconMar.htm and the linked files above? There are other "biological means" to consider... Bob Fenner>

Sea Hare (Dolabella auricularia) question 2/3/05 Hi, We have a local reef club and are thinking of making a group order for the Dolabella auricularia from Blowfish Aquatics. They are supposed to be great algae eaters (will even eat Cyano).  <Good... becoming voracious when large! Although effective, the tremendous appetite of these critters becomes a problem when they deplete the available algae.> The owner of Blowfish says that several have released ink at one time in their tanks with no harm to any fish, etc.  <It is possible that ink release is completely harmless, but keep in mind that your LFS's system is probably at least many hundreds of gallons and may be elaborately filtered. Would this still be harmless in your home aquarium... I don't know. In any case, if you are desperate to solve your algae problems and want to risk it, I would advise running carbon continuously while you have this animal, and be prepared to move them around from aquarist to aquarist as they deplete available food from each tank.> However, we can't find anything on the web that says they do or don't produce deadly toxin when scared or when they die. Before we order, we are hoping you can advise us.  <See this article by Dr. Rob Toonen: http://www.advancedaquarist.com/issues/oct2004/invert.htm and note the interactions listed for various animals that come in contact with the ink. Also note that the size of the system used for the testing is not specified.> Thanks for any help you can provide! <Hope this helps! Best Regards. AdamC.>

Ugg, Slug problems on corals Good Afternoon Mr. Fenner, <Anthony Calfo in your service> Having tried to find some info on the WWW with not too much luck, I was wondering if you could advise me on what to do with a slug problem, I am having in my tank. I live in the UK, and am quite new to marine fish, having kept tropicals for years. My tank is 60 UK gallons, I have live rock, live sand and coral sand as a substrate, >> Livestock >> 1 fox fish >> 5 green Chromis >> 2 percula clowns and bubble tip anemone >> 1 orange spot goby >> 1 small blenny >> 1 dwarf cherub angel and an assortment of soft corals, also have 2 cleaner shrimps, 1 blood shrimp. And a clean up crew of critters i.e.: blue and red hermit crabs, and turbo snails. All of which are doing very well. I am running an Deltec APF600 Protein skimmer,1 UV Sterilizer. I also have 2 large Eheims,  plus an internal filter for the filtration, and 2 power heads for the moving of substrate. And my problem is I have star polyps which are currently infested with these slugs ! they are small and white, and have completely decimated 1 coral, and I am now afraid they will start on the other one. So do you have any advice on how to dispose of them, without using chemicals in the tank, as I am against using anything in the tank, is there a fish or something I could put in that will happily munch on them. <yes... you can use a wrasses species like the six-line wrasse. There are in fact many other species that will work well. The best bet if to move this coral(s) to the quarantine tank while you QT the new fish for 2-4 weeks in isolation. This will force the new fish to eat more and do so faster while the stranded slugs in the display starve without a host> I also use an R/O Unit to make my own water, and I am about to change my salt to tropic Marin, after using Kent sea salt, as I was advised this was a better quality. <A VERY wise move in my opinion> Hope this isn't too long winded ! but I felt if I were to ask an expert, such as yourself you would need to know all the statistics. <you've done an excellent job of providing background information my friend> The tank has been up and running for 7 months now and no losses. Hope to hear soon. Yours Sincerely, Sue Coveney <Sue, to avoid these problems in the future... please be sure to QT all new corals, live rock, etc for 2-4 weeks just like fishes. Else you take a great chance with every piece of livestock added fresh to the display. Best regards, Anthony>

A picture paints a thousand words (hitchhiking slug thing) - 3/26/03 Hi, <Hi Paul here today> Firstly, thank you for providing such a valuable resource for the rest of us. I have an intriguing looking sea slug (or similar) that I would like to put in my main tank but I'm jostling with a little paranoia. <absolutely understandable.> It's history goes like this: I received a shipment of a few pieces of live rock and one of the pieces had punctured its bag, so there was just a little water left around the bottom, when I opened it the smell nearly knocked me over. <Yeah, know the smell well.> At my Wife's directive I put the stinking rock in a tank outside the house and following the directions from Bob's book managed to "re-cure" the rock. <Very good> As the live rock cured a very tiny slug-like creature could be seen in the tank. It is now about 5-6cm long and has been growing like "the blob" It looks just like a garden slug except: it is a mottled light brown colour has small spikes all over it, two feelers, two horns, and a hump on it's back, with  a hole that it can open and close from where it breathes and defecates. <Hmmmmm maybe a limpet.> It's host live rock is now in my main tank and the slug is still in the quarantine tank where it continues to graze on  algae on the sides of the tank as it has always done. <Are you sure it is grazing? Just curious, not discounting your claims> My question is simple: Can I safely put this cool looking creature in my tank? <Not enough information for me to give you sound advice. I would primarily be concerned with positively identifying the animal first and foremost.> I have scoured every source of information, I can find Including Bob Fenner's great book ( which incidentally cost me $160 Australian or about half my take home weekly income!)<Whoa. I am sure he thanks you very much!> which has me freaking out about the horrors, Nudibranchs, Sea Cumbers, etc can cause in a tank. <Very true but they are just fulfilling their purpose in normal stable reef environment. In a closed environment a different result unfolds.> My worry is that I haven't been able to find out if my new friend could do the same or would serve as a loyal cleaner? <Hard to say. Can you send a picture? We really need to identify before any advice for placement could be ascertained> If it is any help the L.R originated in Western Australia, had heaps of Caulerpa Racemosa on it and other macro algae, and during its 're-curing' had countless water changes with natural sea water (yes, I have read that synthetic is preferable- but where I live, 7 hours north of Sydney, the water is pristine and free)<If you get it far from the coast, in my experience. Nearshore/Inshore waters sometimes (read most times) collect inland pollutants. Keep an eye on your water and livestock if used as sometimes your lucky and other times well.....unlucky> I would really appreciate it if you could help dispel my fears. <Please send a picture if you can. Go from there. Even if the picture is someone else's from another site. Identify, identify, identify is the key here! Sorry for the delay, but hopefully you have been able to hold off on placement until you know more. Thanks for the question, Jeremy.> Jeremy.

Sea slug - good or bad? ... the cerata never lie: bad 9/29/03 Hello Anthony! <cheers, Thanassis> I received your book :Reef Invertebrates. It is excellent! Congratulations to you and Bob for the good work! <thanks kindly my friend> Here are a couple of photos of my sea slugs (they are about 10 now) . I hope they are better than the last one I sent you. Thanassis <alas, I must tell you that your sea slug is a carnivorous species... likely to prey on some kind of corals/Cnidarian as evidenced by the cerata on the back (used for storing consumed stinging cells from their prey). If you have any Alcyoniid leathers (finger or mushroom leathers especially) in the tank... I suspect they are viable prey for these slugs. My advice is to remove them. kind regards, Anthony> 

How about a sea slug? The local store has a sea slug they got in yesterday. It is 7 inches long, fleshy, 2 inch tentacles(?), and bright pink w/ light green areas. I couldn't find any hard information on what kind this is and if it is a trouble maker. Any idea? Trisha <This is a big sea slug! Don't know which species... perhaps an Aplysia... please see this tectibranch coverage: http://www.seaslugforum.net/aplyextr.htm I would not buy, try to keep this animal... too much likelihood of trouble... it being cold water, having a narrow diet/food preference... too great a likelihood of it dying, polluting your tank. Bob Fenner>

Re: Giant, Mystery Sea Slug Thank you for the advice. Man it is really a beauty. Hard to resist but not worth the trouble. Trisha <We share the same opinions. Bob Fenner>

Sea Slugs; get rid or not to get rid?! Hi Guys, thanks for your previous help, been of great use!. Just a quick question , after reading up on the Opisthobranchs and the like I still have not come to a decision on whether I should get rid or keep! Background: Last week one very small 3-4mm white and yellow shell less slug found sliming across the front glass, a couple of days later 3 white and yellow shimmy's , a couple of days later 6 shimy's, and what look like coiled laid eggs! Could there be a pattern emerging?! Should I try and remove them or let them get eaten. Many Thanks for your help <lets ID the slugs family/group first to get an indication of what it might eat. Please notice the distinguishing features/structures listed here on WWM between groups... check http://www.seaslugforum.net for comprehensive IDs. Also... look to see if your slug has "tassels" on its back... (cerata)... if so... your slug is a predator on cnidarians like coral. Best regards, Anthony>

Reef Safe Nudibranch - 3/28/03 I am very sorry I tried to look this up but either I am looking in the wrong places or I am blind. <No problem> I just want to know if they are reef safe. <Elysia (sometimes referred as Tridachia) crispata are known to be reef safe. Check on the forums at the many reef sites and more importantly check out http://www.seaslugforum.net and http://www.wetwebmedia.com/grnalgcont2.htm Please take the time to learn about the environmental conditions and the specific needs of this useful but delicate animal> My LFS has a real nice looking one and I want it but don't want to loose coral. Any help is appreciated. <No worries. Paul> Shane

C. varians Hi Bob, I have had a problem with the ubiquitous Planaria a.k.a. flatworms, and have purchased two C. varians to try to combat the problem. I have turned off my power heads until I can get foam filters on them, but am wondering if there could be any critter in my tank that might like a C. varians for lunch. Can you tell me what might "go after" my little flatworm eaters? <Any number of worms of different phyla, crustaceans of size if they're hungry. Where did you get this Chelidonura? Bob Fenner> Thanks, Marty
Re: C. varians
Hi again Bob, Well I do have some small crabs that I bought from GARF. I don't recall what type they are so I have attached a pic. Other than some snails, that's it for sessile inverts <Umm, actually these aren't "sessile"... that is, they live on the bottom, but aren't "attached" to it permanently... so they should be able to keep out of the way> other than what's living in my sand bed. As to where I got them, your friends at FFExpress. They were quite pricey, but if they do the job I'll be happy. <We'll see... Bob Fenner> Thanks, Marty

Carnivorous sea slugs 10/18/03 Dear Anthony, I removed about 15 slugs as soon as you advised me so, but after a week I realized that they are really many of them in my tank, the tank is full of baby slugs. Any advice how to remove them ? <I', confident that diligent manual removal for the next week or two will eradicate them. Natural predators are fewer in number and without a specific ID of the slug, I could not recommend one at any rate. No worries though, I still feel that manual extraction (by siphon... never by hand as some are poisonous) is the best solution. Best of luck (and always remember to quarantine new rock/sand/fish/coral after this <G>!). Anthony>

Half of a sea slug 3/28/04 Hi, How are you guys? <swanky> Thanks for the answer about filter media. I have a strange sort of a question. Nearly a month ago I discovered a small sea slug  on a piece of LR, after reading about their potential deadliness, (from your site) say if they die in your tank I have been watching him closely. <there is at least some slight reason for concern here. Do be cautious> It appears he eats hair algae and has subsequently tripled in size and begun freely roaming the tank. Yesterday I saw him suspiciously close to the input hose of my Fluval 404, by the time I next checked he had disappeared and I did not see him for the rest of the day. My paranoia drove me to check my filter and I discovered him inside. After having to pull all the media out, I rescued him only to find more then half of him was missing. He was still getting about fine so I put him back in the tank. Its the next day and he is calmly back to eating algae. I was wondering if its possible he will survive (longer then he has) and how much a problem the missing half will be. <it may survive and heal/regenerate... although these are natural short-lived organisms to begin with (months)> I have looked everywhere for his missing half and while he is only about an inch and a half (original length) I'm a bit worried what impact it might have, even though it may be in the filter. I was also wondering, I bought a brown bubble tip anemone three days ago and it has been hiding (tentacle and bubble tips looking fat and normal) under a poorly lit cave, is it just acclimatizing or should I be worried (if it matters I have only two 40w fluor lights, one blue, in a 60g tank). <really no worries... such small matter. Simply do a large water change or two in the next week for safety> I have had a small phosphate jump up to 0.25 (which I am bringing down) but all other tests are fine. Is it also true that tanks go through different stages of algae growth while they are maturing? <yes... it is called algal succession. It is natural an inevitable. We describe it at some great length in our plants and algae chapter in our book "Reef Invertebrates"> Sorry about the length of the question and thanks a lot for your assistance - Mr. Blue <kindly, Anthony Calfo>

Sea Slugs I saw these guys for sale at Foster and Smith. They look cool, but other than on their site, I can't seem to find much info on captive care. Are they good for the friendly neighborhood reef tank?  Any information would be much appreciated. <Matt, here is a link that will take care of you. http://www.seaslug.info/factsheet.cfm?base=hamicymb. James (Salty Dog)> Thanks  <You're welcome> 

Sea slug Toxin? Oh yes  02-05-06 Morning guys! <Too cheerful...!> Just found your web sight and it's now booked marked! <And the site too?> I've been searching all over the web trying to find an answer to my problem! About a month ago I purchased a beautiful sea slug. A week later I found it dead, caught in my filter. <Yikes... am trying to put away the pix from the last trip... and am on to the Opisthobranchs... and reading re just how toxic some of them are... no wonder they can be so gorgeously colored and not predated, eh?> A week later all my fish except for one damsel were dead! ( Niger Trigger, reef beauty, Butterflyfish, cardinal, yellow tang) I forgot to mention that my tank is a combo reef/fish 50 gallon. My soft coals and one Anemone were not affected nor were the cleaner shrimp, hermit crabs and turbo-snails. I immediately suspected the death of the sea slug and sure enough read that these slugs secret a defensive toxin. <Yes... but not so much a secret to the fishes they're found with... just in the confines of an aquarium...> I performed a 50% water change and replaced all my filters. I let the tank "stand" for 3 weeks then introduced one blenny to the tank. Within 36 hours it died! It's skin was sloughing off and fins looked as if they were dissolving. <Yep> My question is; should I completely start over with new live sand and live rock??? ( the rock is still very purple in color) or let the tank recycle for a longer period of time???? HELP! Great sight, Jim <Mmm, if it were me, mine I'd try adding a good quantity, quality of activated carbon in your filter flow path, let another few weeks go by and try some other "test fishes". Bob Fenner>

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