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FAQs about Hermit Crabs: Paguristes cadenati, Scarlet or Red-Legged Hermit

Related Articles: Hermit Crabs, Crabs, Marine Scavengers, Fresh to Brackish Crabs,

Related FAQs: Hermits 1, Hermit Crabs 2, Hermit Crabs 3, Hermit ID, Hermit Behavior, Hermit Compatibility, Hermit Selection, Hermit Systems, Hermit Feeding, Hermit Reproduction, Hermit Disease/Health, Land Hermit Crabs, Squat Lobsters, Micro-Crustaceans, Amphipods, Copepods, Mysids, Hermit Crabs, Shrimps, Cleaner Shrimps, Banded Coral Shrimp, Mantis Shrimp, Anemone Eating Shrimp, Marine Scavengers, Crustacean Identification, Crustacean Selection, Crustacean Behavior, Crustacean Compatibility, Crustacean Systems, Crustacean Feeding, Crustacean Disease, Crustacean Reproduction,
FAQs: By species: Calcinus laevimanus (Zebra, Left-handed Hermit), Clibanarius tricolor (Blue-Legs), Clibanarius vittatus (a common Gulf of Mexico hermit crab), Dardanus megistos (Shell-Breaking Reef, White-spot, Fuzzy Leg Hermit Crab), Petrochirus diogenes (a Giant Hermit Crab), & Anemone Hermits, Sponge/Staghorn/Coral house Hermits, Unknown/Wild-collected,

Marine hermit crab burying itself in the sand 9/16/10
<Good morrow Lea>
My tank is doing wonderfully thanks to the wet web media crew - I greatly appreciate all your help!
<We're glad to share>
My current question concerns one of my red-legged hermit crabs. For the past week he has been burying himself beside a particular rock - shell and all. The first time I noticed it I thought he was dead so went to remove him and saw his legs retract so left him in the tank, though put him in a different spot and pushed sand around to fill in the depression. The very next day he was back at it. He seems to bury his shell in the substrate (aragonite live sand), leaving the opening facing out so he can extend his legs and antennae. As far as I can tell he doesn't move, though he may at night when the lights are off. He is situated immediately under a spot where one of my live rocks is disintegrating (and seems to be doing a spectacular job of taking care of the unsightly "dust"). I'm thinking he's found a spot where he likes and has dug in to claim it as his own. Any thoughts?
<Mmm, could be protecting its shell from competitors (other Hermits), or be hiding from predators...>
Have you heard of this before?
<Oh yes>
I know land hermit crabs like to bury themselves when molting, but he doesn't appear to be molting (being in his shell and all). but who knows. Maybe you? :) Oh, and for what it's worth, the other red-legged hermit and my blue-legged hermits are all doing fine and roam about constantly.
Thanks again!
<Thanks for this report. Bob Fenner>

Scarlet Reef Hermit Crab Question/Hermit Crab/Compatibility 6/30/10
<Hello Camron>
I am planning a 12 gal. saltwater tank. I currently have 3 saltwater snails (a Nassarius, a Cerith, and a Nerite) in a temporary 1.5 gal. tank (until I get the 12 gal. set up). I plan on placing these snails in the 12 gal. tank with 1 Tailspot Blenny.
<Ah, one of my favorite blennies.>
With the snails and the blenny in the aquarium, would there be room to include 1 scarlet reef hermit crab?
<Certainly, and is a peaceful crab if you are referring to Paguristes cadenati.>
I am interested in this species because they are not as "aggressive" as other hermit crabs (or so I have been told). Would I have room for the Scarlet Reef Crab, the 3 snails, and the blenny in the 12 gal. tank? Or would I be overstocking?
<You would not be overstocking.>
Thank You.
<You're welcome. James (Salty Dog)>

Red Legged Hermit Crab/Compatibility 11/09/07 Hi, <Hello mystery writer> I was wondering if you ever heard of red legged hermits eating Turbo Snails? I've had my tank running for about a year and have had no major problems. All of a sudden in the last 2-3 weeks I've lost about 5 snails. So I purchased a few more 3 days ago, and looked in today to find a red leg eating one. <If your Red Legged Hermit Crabs are the Calcinus sp., all should be fine. If Dardanus or Ciliopagarus, no, they are known to attack and eat snails. All hermit crabs will eat dead animal tissue and it's possible that the snail was already dead when you observed the crab eating it. Read here and linked files above. http://www.wetwebmedia.com/marine/inverts/arthropoda/crabs/hermitcrabs.htm> Also I have a green hair algae growing out of control any suggestions other than chemical? <Read here and linked files above. http://www.wetwebmedia.com/algaeconMar.htm James (Salty Dog)> Cal. 440 Mag. 1076 Alk. 11.6 Amm. 0 Nitrites 0 Nitrates 5

Scarlet hermit crabs ganged up on Mandarin? 1/19/07 Hi, <Hi> I have a quick question about scarlet hermit crabs. I know they are good to have in a reef and they are supposed to be less aggressive then other hermit crabs. I saw to my dismay this morning four of my large scarlet hermits tearing apart my small twin spot mandarin!!! The mandarin has been in my tank for about a year or more and was doing very well. I hadn't seen any sign of him being sick. Could the Scarlets have grabbed a hold of him while he was resting at night or would it be more likely that for some unknown reason he died and the Scarlets were just doing there job? <The latter is much more likely unless they are very large. They do not work together to bring down larger prey which would be necessary in this case.> At this point in time I'm inclined to take all of my larger Scarlets out and trade them in for smaller ones. I've had a few small fish die here recently and I'm not sure if it's because of the some tank condition or if these Scarlets are just more aggressive when they get big. <Would look for other causes here.> Craig <Chris>

Can I raise baby hermits? 1/5/07 Ok < Graham with you tonight.> I've searched and searched but still can't find out what I'm supposed to feed 1 thousand baby red legs / hermits! < http://www.wetwebmedia.com/hermitreprofaqs.htm > Yes this is the first time I've emailed before , I'm only 13! <Awesome! Good to have some young blood in the hobby.> So exactly what do I need to do with 4 soon to be mother hermit crabs? how long does it take for the once hatched babies to even start looking like their parents instead of shrimp / hermit crab? What do I feed them and how? <Try Google-ing on this site only, and see what you come up with.> I have two reef tanks: a 55 gal and a 20 gal. The 55 acrylic has 1 male Yellow Sailfin Tang who does not like my dad, two Black Ocellaris clownfish 1 male and one evil female who means murder every time my hand or anything else besides the bubble tip is in the tank or is put into the tank!! One 4 inch Mithrax <You mean Mithrax, like the crabs?> -male , 2-inch female , and a 1- inch female. Tons of clams, long story short it's a true reef, but without problems!! <Good to hear. Not often do I read that.> We even lost power for FIVE DAYS , AND NOTHING BUT THE CLEANER SHRIMP DIED , crushed by a falling rock !! <Aww...> Ahh the evil clownfish and male Mithrax + the Tang are having war, came a little to close to the host !! Got to go!!!!!!!!!!!! <Good to hear from you, hehe. Spread peace! (...Mithrax???) -Graham T. >

Coralline Algae and Hermits a-chomping 5/2/06 Hi Crew and thanks for helping all of us! <Hello back at you! Jodie here once again on this fine and stormy evening.> We have a 30 gallon tank with 30 pounds of live sand and about 40 pounds of live rock. We have 4 very small fish and around 30 hermit crabs. <What kind?> In spite of all of our efforts, we can't get the rocks to "purple" with coralline algae. A year and a half ago, we added a 120 watt lamp. The rocks look darker now, but not purple. My wife has noticed at the local fish shop that the tanks that have nice purple rocks have no hermit crabs. She's convinced our crabs are eating the coralline algae. <She could be right...> I insist otherwise. <...but so could you.> Which one of us is correct so we can settle our wager? <Hermit crabs, especially red-legged ones, could be eating the coralline if they are lacking in food. I would check your parameters first though, before blaming them. Low magnesium levels can hinder coralline growth, as can nuisance algae, poor water circulation, urchins, etc.) Thanks for all of your great advise! <Sorry I couldn't definitively settle your bet. Too many variables for me to make a solid judgment. Cheerio, Jodie> Charlie

Cirrhilabrus Wrasse Compatibility with Hermit Crabs 3/3/06 Thank you WWM Crew for all your past advice. Two of my Red Legged Hermit Crabs (Paguristes cadenati) disagree with the common fact that Cirrhilabrus Wrasses are "Reef Safe." <Heee heee... who's "right?"> My Social Fairy Wrasse (Cirrhilabrus rubriventralis) must have gotten bored and ate up some free-range fish food. <Yee hah! Get along little anomurans!> It was no great loss (But a great show.) I post this experience just so others can know and so they will not get terrified if one of there Cirrhilabrus Wrasses takes down a tank mate. <Thanks> One thing, he has never eaten one of the Blue legged hermit crabs (Clibanarius tricolor) ??? <Not as tasty? Might if hungry enough. A point in lesson here: "All animals, as species, individuals are only to some degree "safe" or no"... Thank you for sharing. Bob Fenner>

Molting mishap? 1/18/06 Hello Crew! <Laura> Firstly, I just love your site--the amount of information that you have shared is amazing! <Lots of good help> I have searched your archives but I can't find an answer to my question; I hope that someone can help. I have a 20-gallon marine tank, which has been problem-free. I do weekly water changes and check the water conditions with a home test kit. After doing partial water change this morning, along with the weekly dose of iodine, I noticed that my beloved red-legged hermit crab, Senor Crabs, seems to be having some difficulties molting. <Very hard to match water quality with such a small system... and slight differences in chemistry, physics...> I wasn't aware that they molt during the day, <Night or day> so it was quite a surprise to see it happen. Everything looked normal at first--his old body was out of the shell and a white sheath was attached to the old exoskeleton. The sheath was moving, so I assumed that Senor Crabs was in there and would be making an appearance soon. I went out for a few hours and returned home to find a hitchhiker snail sitting on the poor crab, which it is totally out of the shell, just laying on the sand. The white sheath is still attached to the old exoskeleton and I can see something dark inside the sheath. Is this the end of Senor Crabs? How long does a molt usually take? Thank you, Laura <Minutes to a few hours... You do have sufficient alkalinity, alkaline earth content? Perhaps this Hermit is/was "just" old... Do hold out... it may be still about... elsewhere. Bob Fenner>

Hermit Die-Off (4/19/04) Hi, I seem to be having a problem with my 6 scarlet reef hermits. I have had them for two months now. I bought them a month after cycling the tank. They are in a 72 gallon saltwater tank with 75 lbs of live rock ( that was fully cured before introducing the crabs ). A week ago, I lost the first one. He had crawled out of his shell and was halfway across the tank where I found him dead. Two days later, I lost another one. He was in his shell, but hanging out of it, dead. Two days after that, I lost another one. Same scenario, hanging out of his shell dead. Then this morning I found a fourth dead, hanging out of his shell. The water parameters are all 0. (Nitrates, Nitrites and the like). <what is the specific gravity?--all inverts tend to do better closer to normal seawater. pH? Tem? Are these all stable?> This tank has been running for 2 and a half months. No fish yet. ( Still in quarantine, they came in sick. ) I add iodine once a week for molting ( I also have a camel and a blood shrimp. I lost my peppermint to what appeared to be a molting problem, so I bought the iodine.) <Best to test levels of anything you add.> I have a dozen or so dwarf blue, red and zebra crabs. They are all fine. My shrimp and snails are good too. Three weeks ago, I did receive an order that included the red legged and zebra crabs, as well as an electric blue crab. Everyone is fine but the electric blue did die a week after he arrived. I also lost the banded Trochus snail that came with that order as well ( He, actually I believe she, had just laid eggs the day before she died. ) On two of the crab shells, I found what I thought were small feather duster worms, but I was told it was Aiptasia. Could that have been the problem? <Harmless to the hermit, but can be a big problem for the tank--read the Aiptasia FAQs.> I see nothing wrong here otherwise. I have over 2 dozen shells of all sizes in the tank, so it was not territorial aggression. My Scarlets have spawned three times in the last month. Is this normal afterwards? <Some inverts die after reproducing, others do not. I am uncertain about hermits.> What is there average lifespan? <I'd guess at least a couple of years--some a decade more.> Could they all just be old? <Possible, not probable.> I bought them all at the same time from the same store. Is there maybe something that came in on the new stock, that is effecting just the Scarlets? <The fact that it is not affecting your other crabs and shrimp does suggest something specific to them rather than a more generalized toxin or pathogen, but I am not aware of a pathogen specific to this species.> They are my favorite and I would love to get more, but I want to make sure that the new ones won't have the same fate. Sorry for the lengthy email, but this is breaking my heart. <It's always tough to lose animals, no matter how "primitive," especially when the cause remains a mystery.> I am trying so hard on this tank, and everything that can go wrong, appears to be doing so. Thank for the info. <I'm stumped here with this scenario. I'd suggest you start a topic on the WetWebFotos forum under "Marine Invertebrates" and see k a range of opinions/theories there. Steve Allen.>

Marine Hermit crab reproduction methods - 7/28/03 Hello WWM Crew,<Hello there. Paul Mansur here today> I'm a long time reader and fan of the site. <Fantastic. Glad to hear> This is my first time writing (because the site is so darn comprehensive and all my other questions have been answered before!). I have 2 scarlet reef hermits in my 10g Nano and just want to know if they are hermaphrodites or distinctly male or female. My guess is the former, but their behavior makes me wonder. I think I have seen them mating. They both went down into a big, secluded hole in the live rock and faced each other and sort of interlocked legs and came partially out of their shells so the soft parts were exposed. One crab is much larger and more aggressive and was dominant during this "interaction". The smaller more passive crab is the one I later saw releasing tiny larvae at night (I was shining a flashlight on it). They have spawned a couple times already. I can't seem to find an answer about if they are dioecious or hermaphrodite in my books (I have books by Fenner, Delbeek and Sprung, Tullock, et al). I know this isn't of earth shattering importance, but I was just curious. Thanks in advance! -Ken <Well Ken. I think I have an answer for you but it is based on California species (roughly applies to tropical species as well). This is the answer I personally received today from an associate of mine Dr. Robert Toonen Assistant Research Professor, University of Hawaii at Manoa School of Ocean and Earth Science and Technology, The Hawai'i Institute of Marine Biology I hope this helps. It does correlate with your findings: "There is quite a bit of variability among different hermit crabs in their mating behavior, but I'll try to give you some reasonable generalizations. At least the larvae are relatively easy to raise by comparison to most inverts. I've never raised any of the popular aquarium species (like blue- or red-legs), but I've raised several of the local CA species. With one exception, all the hermit crab species with which I am familiar brood their larvae externally (but within the shell) until they complete the nauplius stages (early stage larvae, similar to a baby brine shrimp), this period can vary between about 1 and 12 months, depending on the species. The females then release either zoea or megalopae (just fancy words for more-and-more mature larval stages) which typically feed on phyto- and zooplankton. Depending on the species, this planktonic larval stage can last days to months. Because the youngest stages are brooded within the shell, and because rearing of the later-stage larvae is relatively simple by comparison, hermits are a good choice for an attempt at breeding tank critters at home." "Hermits have separate sexes with relatively little sexual dimorphism. The best I can offer is that, in general, the males tend to be larger than the females and in some species the chelipeds (claws) are larger on the males. Hermits often have elaborate mating behaviors (displays, shell knocking and such) during which the male will guard the female until she releases the prior brood that she is carrying. Thus, in the aquarium, when people see this, they report a larger hermit "messing" with a smaller one, and suddenly the smaller one sprays out a stream of larvae. Once the brood is released, the female typically molts prior to copulation (which is why the male guards her) and extruding their next brood. During copulation, the male attaches dozens to hundreds of spermatophores (packets of sperm) to the "abdomen" of the female, and eggs are fertilized as the female releases them prior to attachment to the "abdomen." The male then moves on (this "courting" period can take anywhere from several hours to a week or more in some species), and the female then carries a colorful brood of fertilized eggs on her "abdomen" (or more correctly on the pleopods) within the shell for anywhere from several weeks to a year or so, during which time she constantly cleans and ventilates the developing young." "The larval duration depends on the stage at which the brooded larvae are released. The larvae typically go through something like 1 prezoeal stage, 4 zooeal stages, 1 megalopal stage and a final decapodid stage of development before becoming a tiny "adult" (although this again varies by species). In most species, the prezoea and some variable number of zoeal stages are completed while the mother broods the young, until they are released (usually around 2 mm in length) and the planktonic larvae spend something like 20-90 days as a feeding larvae before molting into the decapodid stage (which is capable of both planktonic and benthic life). During this time the larvae feed on phytoplankton but usually prefer small zooplankters (such as rotifers, ciliates and the larvae of other invertebrates) when they can get them. There are some exceptions in which the larvae are nonfeeding, and spend a relatively short time in the plankton (several days to a week or two), but these cases are relatively rare compared to the number of species that produce the feeding stages, and I don't know of any tropical examples of this off the top of my head. So, if you wanna raise hermits for a reef aquarium, chances are good that you'll have some intermediate- to late stage larvae released by the brooding parent, and will have to feed them until they complete their development...Hope that helps...Rob" By the way, this is from an email to me, Paul Mansur, personally and no reproduction other than the use of it by WetWebMedia is acceptable. Expressed written consent is necessary for its duplication by Rob Toonen. Thanks for your understanding.

When Good Crabs Go Bad...Live on WWM 3/19/03 Hello!
<Hey! You got Phil tonight!> My red legged hermit ate my blenny and a snail.
<Oh no.. are you sure.. did you see it happen?>
I first suspected my fiddler crab, but I read they don't kill fish, because they are herbivores. My question is, How the heck he could have done it (to the blenny) with his little claws (he is 1/2")? He ate the whole thing.
<I doubt that he killed it. More likely the fish died and the crab(s) ate the remains. I have seen that happen, but have never seen a crab kill a fish. It happens but I doubt it in this case. Good luck and sorry about your loss!> Thanks
<No problem! Phil>

hermit crabs, repro.!
I enjoyed your answer to the questions about hermit crabs mating. We have the red legged crabs and evidently missed the whole mating thing and now have a hundred?? baby hermit crabs in our 50 gallon tank, do we need to do anything for them?
<Mmm, yes. Feed them... keep potential predators away...>
Will they get eaten by the other crabs or fish?
They seem to be trying to get out of the tank?
<What they do... are not totally aquatic... More amphibious>
Any info you can give would be helpful. Thanks
<Welcome. Bob Fenner>
Re: hermit crabs, repro. -- 08/23/09

What do you feed such tiny little crabs? Is there a mini food or what?
<Small foods of many sorts will suffice. Scan the Net re Anomuran culture.

- Healing Hermit - Hi there, <Hi, JasonC here...> I have a red legged Hermit crab which I am really worried about. He did he usual hiding before shedding. Disappeared into his nice little cave I made for him. He shed his skin late Friday night. I noticed he was hiding inside his shell on Sat. He usually remains grumpy for about a week after shedding. However on Sun he came out of his shell and was missing his big pincher and all his legs down the left side. I don't know if one of the fish pulled him while he was weak or if he just decided it was a good time to loose his shell. <Dropping a limb is an ability crabs and lobsters have that allows them to get away while leaving something behind to distract/appease the predator.> I left him in the tank to reduce his stress however I noticed that some of the fish were bothering him. So I moved him into the sump. He seems to be fine and he is eating etc. I have knocked the calcium level a bit higher to give him more calcium to recover. Don't know if this will help. Is there anything that I can do to help him heal faster. <Not really, you did the best thing by removing the crab to a quiet place to stave off aggression. The limbs will grow back with successive molts. No worries.> Thanks, Rob. <Cheers, J -- >

Hermit Crab Genocide? Dear WWM, I always start my emails with a thank you for all you're doing. So, once again, thanks! <Welcome> As I am about to discuss the health (or lack thereof) of my hermit crabs, keep in mind that all my fish are doing fine, and that Am, trites are at 0, trates are minimal, SG and pH are fine. <Okay> Anyway. My 2-month-old 30-gal SW aquarium cycled beautifully with Live Rock, two weeks after which I added two paired clowns. Two weeks thereafter I added a royal Gramma (who had a bit of an adventure getting into the tank, jumped out of the transition container and onto my carpet), but after a few days in hiding, he's now king of the tank, not at all shy, and gets along with my clowns. I decided to add some sand sifters... my LFS recommended I get 5 red-legged hermit crabs. They assured me these guys were very hardy and did not need to be QT'ed or acclimated. The crabs did fine at first. They were all very active, constantly going through my sand and climbing through my LR. A while later, my LFS recommended I add Calcium and Alkalinity to my tank to make it suitable for corals. Well, ever since I added these two components, my hermits have slowed down considerably. They don't move around any more. <Good observation> I thought they were dead, but when I look closely, their little "antennae" (or whatever they have between their eyes) still move around. However, one of the crabs, I found this morning, sprawled out on the sand, out of his shell. I'm not sure how much of a body they have besides the red legs that we see when they're in their shells, but this guy did not have much of anything left besides his legs. <There is not much to these anomurans> When I tried taking him out of the tank, his legs separated from each other! <Uhh, dead> I'm baffled as to what happened to him. It almost looks like the rest of his body was eaten. Is this guy's decision to crawl out of shell in any way related to the deterioration in activity of the other crabs? <Not likely... very likely due to the alkaline reserve and calcium addition/s> Is it possible these guys' health was anyway going downhill and coincided with me adding the two components? Or is their health downturn directly resulting from the chemicals? <The latter> I liked these guys, too. :( Your responses are, as always, greatly appreciated. Paul Ghica <Please read here: http://wetwebmedia.com/hermitdisfaqs.htm and on to the Related FAQs (linked, above, in blue). Bob Fenner>
Re: Hermit Crab Genocide?
Thank you for your responses, Bob! <Welcome> I decided to discontinue my Alkalinity and Calcium treatment of my tank for the sake of my hermits. <A good idea> Now, the story below comes with a twisted development. I thought one of my 5 crabs died. I saw his shell-less body sprawled out on the floor of the aquarium. The same thing happened to another one of my hermits. Body on the floor. Within two days, it was broken apart, presumably eaten. That should leave me with 3 hermits, right? However, I just counted 4 crabs crawling along today. <Hee heee! I smell a molt> All 4 that I saw were pretty big, so that rules out the possibility of a baby. Two of them were still pretty motionless, except for their little antennae moving around... now, the other two have gotten simply huge, have seemingly almost outgrown their shells, and are quite active, climbing anything they possibly can. I'm starting to think that those were not crabs I saw on the floor, but just their molts (is that what they're called when they "shed"?). <Yep> My apologies in advance for any poor terminology I may use. I still don't know where to find the elusive 5th crab, or his shell. Is there anyway to make my tank reef-ready (my LFS insists I must add Alkalinity and Calcium in order to do so) without further endangering my hermits? It seems their health and activity is directly related to my adding the chemicals. <Best to not add anything at this point.> Now, of the four I currently see inside in the tank, is there a correlation between the fact that two are bigger and active, two are still small and inactive, and that there are two molts on the floor? <Likely the larger ones are growing faster... do make some assortment of shells available for their use> If there might be some link, which two are most likely to have recently shed? The active ones, or the inactive ones? <The active> The reason I ask is because if the active ones are the ones whose molts are on the ground, perhaps I can look forward to the others molting and becoming bigger and active. If the inactive ones are the ones whose molts are on the ground, I'll presumably need to do something before my two remaining active crabs meet the same comatose fate. <Yes, they all will molt... every few months... slower with age, larger size> Thank you for sharing your wealth of knowledge. Paul Ghica <Glad to share. Bob Fenner>

Scarlet reef hermit Bob, I have been using the website to help me with a lot of questions, its great! My question is, Do Scarlet reef hermit crabs molt their hard bodies, I know they switch shells when they grow out of their current ones, however this morning when I looked into the tank I saw what looked to be the body of one without the shell laying on the Live rock is this common and nothing to be alarmed about or do I need to go on a mission to find the killer? <All crustaceans, including the Hermits undergo ecdysis (molting) to allow for (generally positive) growth... and often leave their old exoskeletons about (better to leave in the tank as the old owner may ingest/incorporate the matter into its new one... and it won't pollute your system).> Thanks as always, Mike <The next few days after molting are dangerous for the "soft bodied Hermit"... don't disturb the landscape if you can avoid it. Bob Fenner>
Re: scarlet reef hermit
Bob, Thanks for the ultra fast reply!!!!! One last Question what does the molted exoskeleton look like? <Initially, like an exact model of the original... sans the insides... eventually, just bits and pieces...> I'll try to describe it the best I can. The legs are red, and look exactly like the legs on a living crab, same red color/length, the abdomen looks pale white, almost a milky color and seems to wave in the current freely, it appears it has those small legs use to move in and out of the shell, however its not too large in size, but then either was the hermit to start, and its laying upside down. I don't know how greatly this will help but I'm so concerned for in the case its dead, ill need to make sure its not something in the tank killing them. <Might be a molt... with some of the mineral and matrix content going... Not to worry. Bob Fenner> thanks, mike

Red Slime Algae Hi Bob, Haven't written in quite some time. I have a case of Red Slime Algae. I've neglected my tank over the summer (I've been a bad boy) and now I'm going to remedy it through large water changes every week. I know what needs to be done, but I've seen claims from a few "sellers" that Red Leg Hermits eat red slime algae. Have you ever seen this? <highly unlikely... it is a noxious Cyanobacteria disdained by most and fatal to some. Aggressive protein skimming can also eliminate this problem in mere weeks. Seek to get daily dark skimmate from your protein skimmer.> Thanks, Tony <best regards, Anthony>

Hiding Hermits - Hello Again Devin Hello everyone, I have a question regarding hermit crabs today. I purchased 4 red leg hermit crabs 4 days ago, and they have been having quite a feast with my algae on my LR. Today, however, I noticed only 2, and after looking around I found the missing ones. They were tucked under a large piece of rock right next to each other, not moving. They have been in the same position for almost a day now and I am wondering if they are okay. could it be that they are mating? If you have any advice or info, it would be most appreciated. Thank you. Devin O'Dea PS. (my tank is 29 gal) <Devin, please read over our materials archived on Hermits, here: http://wetwebmedia.com/marind5_5.htm. Scroll down to... Hermits... Your animals may be hiding, may have molted, may be dead... from? Incompatible water quality, a hidden predator... Bob Fenner>

Scarlet Hermit Crabs Hi CREW, <Hello Debi> I understand Scarlet Hermits need to go looking for a new shell as they grow. <Correct> So how many empty shells should I provide and where is it best to place them to assure happy hunting? Is it ok to get shells from a shell shop as long as I boil the empties before putting them in the tank? <Four or five empty shells should be enough. Choose various sizes that are slightly larger than the home he is in. I believe shells from a shell shop would be OK. You want to pick shells that are similar in shape to the one he is in now. I would not use any if they were sprayed with a clear coat or anything like that. James (Salty Dog)>

Little Blue I really enjoy your web site and find it very useful.
<As do I! Ryan helping out today!> Can you house blue legged hermit crabs with red scarlet hermits? I have a 55 gallon reef tank with 75lbs of live rock. The store manager at the place I buy my products says one will eat the other. Is this true? <It's not unheard of, especially when competition for shells is fierce or the scarlet is much bigger. Many crabs are omnivores in the true sense- they'll eat anything. Could really go either way. Good luck-Ryan>

- Crab Parts - Hi gang, <And hello to you, JasonC here...> I have four red leg crabs in my 30 gallon fish only aquarium. Water is perfect temp is great. But every so often I will see a crab leg floating in the water on lying on the sand. Do they molt or shed legs? <They do molt although it is usually their entire body, and they can also autotomize [self-amputate] a limb if they need to make a fast getaway.> I have not noticed anyone picking at them. <Could be it all went down while the lights were out... I wouldn't be too concerned.> Thanks Christina <Cheers, J -- >

Scarlet Hermit Deaths >Hi, >>Hi. >We are new to this hobby and your website has been a tremendous help! However, we have a mystery that we can't seem to find an answer for. >>Thank you, you're welcome, and let's see what can be done. >After the tank cycled and the algae bloom subsided, we were left with a few small patches of hair algae and some areas of brown diatom algae. 2 weeks ago, we purchased our first clean-up critters from JEF. 6 tapestry snails and 10 scarlet hermits. 2 scarlet hermits died the second day. pH and Alkalinity were low (7.8 and 2.1 respectively), so we slowly added Seachem pH buffer. >>Hhmm... pH is a tricky thing to be messing with. I wouldn't make changes any larger than .1-.2/day. The pH is indeed low, but what about specific gravity? >The scarlet hermits have continued to die - one or two every few days. We left the bodies in the tank, just in case it was molting. Most of the time they had crawled out of their shells - and their little bodies were still in tact for days (so we assumed it was not a predator). The really weird thing is that eight of them came to the same area of the tank to die (within inches of each other)!!! >>No answers to that. >We lost the last one today. He had been really active and was on top of a large rock eating yesterday. Today, his shell was empty and a 3 inch long bristle worm came out of it. He is the only one that has apparently died at the other end of the tank (one is still missing). All six of the tapestry snails seem perfectly fine. A friend offered to give us a few scarlet cleaner shrimp. Now we are afraid to take them (don't want to risk their health). Can you help us figure out what to do? Also, should be buy a wrasse get rid of the bristle worms? >>No, the worms are there for a reason, and they do perform a function. If they seem to be of "plague" proportions, you definitely have a nutrient/excess detritus issue. >Thanks!!! Dave >The tank is a little over 2 months old - 110 gallon (29 inches tall) with about 85 lbs of live rock and an ecosystem filter (with Caulerpa) sg 1.24 (swing arm tester) >>Poor choice for a measuring tool, in my opinion. temp 80 Alk 4.8 pH 3.0 >>This can't possibly be right, can it? >nitrites 0 nitrates 0 >>Curious about test kit brand/reliability. If your specific gravity is indeed spot on, then I am at a bit of a loss, as there is nothing I can think of that would kill only the hermits and nothing else. I would indeed try the shrimps, one, maybe two, just to see. Acclimate slowly and watch. Double check your test kit(s), as well as your hydrometer against something a little more reliable (my own affordable preference are floating hydrometers). Sorry I can't be of more definitive help at this time, but maybe you'll find something by double checking the kits, etc. Marina
What is Killing our Scarlet Hermit Crabs?
>Thanks. We bought a good floating hydrometer. Salinity is right at 1.024. Two people have told us that some worms including certain types of bristle worms are dangerous (can kill). >>Bristle worms will eat what is dead, I doubt very seriously that they are an issue. >We bought an arrow crab that we are very slowly acclimating. Did we make a mistake? Also, if we should keep it - do we need to quarantine it (this early in the reef stage)? Dave >>Personally, I believe in quarantining everything, including inverts. You've purchased the arrow crab to eat the bristle worms? If so, consider instead that the bristle worms perform a function, as well as indicate a possible buildup of detritus, as I mentioned previously. Marina

More Hermit Stocking Questions >Thanks, again, Marina. >>My pleasure, Barb! >When you say two dozen "animals", are you just talking about the invertebrates (in this case hermit crabs) or are you referring to ALL of the tank inhabitants (i.e., including fish)? >>I am referring SPECIFICALLY to total hermit crabs. I feel that Steven Pro's assessment of stocking is quite prudent, and you would do well to follow that advice. >Regardless, I bought 10 dwarf red legged hermits today at a LFS (none around here had any dwarf blue leg or dwarf zebra in stock and Live Aquaria charges $25 for s/h) and put them into the main tank after adjusting them to its temperature. >>Salinity is another VERY important parameter to measure and adjust for, as well as pH (this is more for the people who read the FAQs daily). >Unfortunately, my much larger dwarf red leg hunted two of them down and grabbed hold of them (one at a time). >>Ouch! Son of a GUN! >No matter how many times I relocated the larger one to high live rock or different areas of the tank, he was relentless...and FAST. >>Arghh! Is he a candidate for the "derelict tank"? (These seem to be growing in popularity, and they often seem to do MUCH better than the more dedicated setups! Go figure.) >Their shells were so much smaller than his, I doubt that housing was the issue here. >>Absolutely agreed. But, don't tell me he didn't even EAT them. >I decided to put the big bully into the QT (scrubbed clean, new bio-wheel, perfect water conditions due to the use of a good deal of the water from the main tank). He was originally one of four that we purchased early in the year... a murderer who apparently didn't kill for shells, but for sport! Let's see how he likes solitary confinement! >>Oh lord, I bet he DOES like it.. >If your reference to "animals" was just to crabs, then a few more of another species is surely in order, to prevent brawls. Barb >>Agreed. Did I mention that I have a friend who buys shells at the craft shops? She boils them for a while, then just tosses them into the tank. I know other folks who go scrounging the fish shops and ask for the "dead snail shells", which the shops tend to just give away. I'm very glad that things are going relatively smoothly (murderous hermit crabs aside, of course). Marina

Hermit death sleuthing Alright, I wrote you last week about clown fish and scarlet reef hermits. One of the hermits showed up dead this morning, out of its shell, like it crawled out and then expired. The other one I have not seen today, and though it was quite active on Friday, I am concerned it kicked. Water tests, using an Aquarium Systems test kit yielded the following results--no ammonia, a range of 0.2-2-mg/l of Nitrite and a range of 0-10 mg/l of Nitrates, salinity 1.024 and ph 8.2. Three questions: 1. How long does it take for my tank to do a cycle using cured live rock. Is it possible the tank is already on phase 2 of its cycle even though I only added rock 4 days ago? 2. Was the crab molting and died or what happened--any ideas? 3. I am noticing an increase in the brown diatom algae--what can I adjust in my water to make this go away? Jeff Ranta < 1) Jeff, next time wait on the livestock till your system has completely cycled; zero ammonia and nitrites. Some well- to completely cured Live Rock will present a situation of pre-cycling by itself, but this is rare. In some situations, where the rock has a lot of dead biomass, or is killed off by its handler(s), cycling may be delayed for months... This is why one needs to measure things like ammonia and react (generally with massive water changes) if conditions become deadly (to the live rock organisms). Keep checking your nitrogen cycle parameters; you should find no nitrite and growing nitrates with establishment of cycling. 2) The crab probably died from outright chemical stress, from the die off, and respective changes brought on by the cycling. 3) The Brown scum/diatom algae you mention is a good sign! This indicates succession, cycling that is producing nutrients and viable conditions for other life... I wouldn't disturb it as yet. Wait till you see it being supplanted by Green algae, this will happen soon. Patience my friend, Bob Fenner>

Hermit crabs Hi Mr. Fenner. I have another question once again. Do hermit crabs also molt, or not since they keep looking for bigger shells? <They do indeed molt> I ask this because if they don't molt, then I have something going on in my aquarium that might sound strange. I have six red legged hermits, and two that are very dark, almost black. I've had them for months, and every so often I find what looks like the remains of one of them. I say remains because it looks like they have been eaten, and all that is left is the front part, like the head, and legs. sometimes the remains are red, and other times they are dark, which shows that both types that I have are doing this. It's not a clear shell like when my different types of shrimp molt, but actually looks like the remains of the body. Yet when I take a roll call, all of my hermit crabs are still alive, and well. <Good observations, relating... No worries... keep supplying a selection of "new homes/shells" to move in to. Bob Fenner> Thanks Greg.


Hermit Crab Bob, I have had a Red Legged Hermit crab for approx. 5-6 months in a FO 60ukG tank. All has been OK for those months, as he has been keeping the tank nice and clean and roaming around, occasionally shedding his "skin". Two nights ago I found it on its back and therefore hiding in the shell. I assumed he had fallen off the rocks in the tanks and could not right himself - I waited a while (1-2 hours) but he did not even come out a little bit. I did the honors by placing him right way up but he never seemed to come out of his shell. He came partly out but then retreated somewhat. Last night I discovered that he was in fact dead and therefore removed him from the tank, shell and all. There are no other signs of illness in the tank and no problems with any other fish over the past few months. Water parameters are OK (pH is a bit high - above 8.6) and all other fish are OK! <Hmm, am concerned about how/why your water pH is so high... this could be the very cause of loss... not uncommon that supplement "shock" is for hermits, snails, cucumbers, Seastars...> Could he have been shell shocked?? <Hmm? A 'Nam vet? Not from falling... and no worries re Hermit spatial orientation... healthy ones are very able to right themselves.> Any suggestions? Thanks in advance. Scott <Just to investigate your water conditioning practices, test kits... Bob Fenner>
Bob, Having sent you an e-mail on my Hermit Crab, I meant to add a further question. When making water up for a routine water change I get a "scum" on the top of the water prior to adding it to the tank. I use de-ionized water and add a re-mineral M additive and salt. I then aerate this using a pump for 12-24 hours before changing. It is after this aerating that the scum appears. In order to stop the scum entering the tank on a water change I filter it through a sponge and this seems to work. <The sponge is a good idea... but would aerate, store the new water for a good week... > I have not seen any noticeable affects on the fish or water quality apart from a rise in pH (it was stable at 8.6 from start but now raised to above this). <You need to check your alkaline reserve... I suspect that you have insufficient carbonate, bicarbonate content in your water... and I would vastly cut back on the use of the "M" supplement> Is this normal and is it just being aerated too much or too vigorously?? I am now using the pump from my thrown away SeaClone (replaced with a Turboflotor on your advice - much much better!!) - a 1000l/h pump (I think!) <Not un-normal... but also not a good sign/indication... you don't want to have a permanently elevated pH... many potential problems with this condition...> Is there anything I can do to lower the pH or should I wait and see if it cycles? <Cut back on the supplementing... get involved with the "madness" of adding buffers (precipitating out some of the cause of the high pH...), skip both and get on to using a calcium reactor, just rely on the added biomineral and alkalinity boosting of good salt mix (like the Instant Ocean products)... Really though, gaining an understanding about the aspects of pH, alkalinity and alkaline earth elements, their roles, interactions in captive environments... Please read over the sections and especially FAQs areas on these concepts posted on the site: www.WetWebMedia.com and seek out the books/references mentioned to read over their thorough treatments... buy, use testing... And...> Thanks again for your time, Scott <We'll be chatting. Bob Fenner>

Hermit sick Dear Bob, I've read your archives on alkalinity, pH, hermits, hermits FAQ. Our red reef hermit has been hanging out near/on top of our bubble wand for several days now and I'm getting concerned. He'll usually slow down a bit before he molts but he does not look like he's eating (he usually takes food from my hand) and this has been going on unusually long. He also looks a little pale. Here are our water parameters. Do you think low alkalinity could account for this? <Possibly... you do have a place for it to haul all the way out of the water?> Can you tell me very explicitly how to raise the alkalinity in a way that is safe? <Simple baking soda... oh, I see you know from below...> You mentioned baking soda (we bought Arm and Hammer--are you sure there aren't dangerous additives)? <Hmm, yes... the only ingredient is sodium bicarbonate... you might want to use a test kit if you're concerned... there is very little chance of overdosing though> alkalinity=3 pH=8 ammonia=0 nitrite=0 nitrate=5-10 temp=82-84 salinity=1.022 We've had our tank since January and we're sparsely stocked in a 125 gallon tank with 1 Naso tang, 5 damsels, a cleaner shrimp, and the red reef hermit. We have a few chunks of live rock too. We gave our Naso tang new food a week ago (Spirulina pellets) and that's the only recent change I can think of. Our filtration is a trickle filter with Biobale and a carbon canister. I'm grasping a any other hypotheses. Thanks! Allyson <Mmmm, maybe just a pre-molting incident... Bob Fenner>
Re: hermit sick
Dear Bob, I've read your archives on alkalinity, pH, hermits, hermits FAQ. Our red reef hermit has been hanging out near/on top of our bubble wand for several days now and I'm getting concerned. He'll usually slow down a bit before he molts but he does not look like he's eating (he usually takes food from my hand) and this has been going on unusually long. He also looks a little pale. Here are our water parameters. Do you think low alkalinity could account for this? <Possibly... you do have a place for it to haul all the way out of the water?> You're kidding! I have not read that red reef hermits need to come out of the water! Is this really true? <Some folks dispute the possible benefits, need... but they are found out of the water (where they're collected) in the wild... and this one may need to "dry out" a bit> You don't think that if I take him out of water, he'll die? Hmm. I'm not sure how to engineer something he can climb on. <Good idea... even just a piece of Styrofoam anchored to the upper corner... Bob Fenner> Thanks, Allyson
Re: hermit sick
The little hermit is better!!!! I added 2 tbsp of baking soda last night and alkalinity increased by .5 (to 3.5) and this morning he's waltzing around!!! (although not as energetically as he typically does) My log books showed a slow drop in alkalinity over many months (you mentioned this is common with trickle filters). <Yes, more so than other filter modes> The little fellow must have reached his breaking point. PH might have increased too (not sure-8 to 8.1, hard to tell). I'm going to increase alkalinity a bit more. I'm having trouble finding what is typical in our books but our test kit is saying the value should be 4-6 meq/L but Tullock says it can be lower. <Better to be a bit higher IMO> Wow, thanks. <You're welcome my friend. Bob Fenner> Allyson

A Question of Algae Eating Inverts Dear Robert, <You reached Steven pro today, filling in for Bob.> Thank you for answering my last question. I now have another question. I have hair algae problem, in my 29 gallon tank, can I put red legged hermits with my live rock? Will they destroy my rock? <Scarlet red reef hermit crabs are one of my favorites. They are pretty much strictly algae and detritus feeders. I have never had any problems with these, unlike the blue legged hermit crabs.> I do have a sally light foot crab and was thinking that I should put an emerald crab to help control the hair algae. I know that it is a possibility that they will fight or kill each other, but is this usually the case. <Hard to say for sure. That is why there is a difference in the articles you have read. I would probably advise against both in a 29. Less room for one to get away.> In some articles that I read says that they have different habits and don't usually bother each other. My tank has plenty of hiding places and live sand if that helps any. I do want some more inverts in my tank, what is the route that you would take in my situation. I won't hold you responsible for any decisions that I make, so please give any advice or info that you have. Thanks <I hope I have been helpful. In recap, Scarlets yes, emerald no. -Steven Pro>

Red Legged Hermit Crabs Dear Bob, After looking over the site, you wrote about Dardanus megistos (sp?) as a type of Red Legged Hermit that controls Aiptasia. I have several "Scarlet Reef Hermits" in my 125 FOWLR and DSB. I tried a search but came up empty on the net. Are the Scarlet Reef Hermits the same? <Mmm, no... the latter are almost always Paguristes cadenati... Bob Fenner> Thank you, Jeff

New Hermit Homes I am new to saltwater tank keeping so please bare with my questions. <You are welcome here> I have a red legged hermit crab, he is very small, about a half an inch. I have read on your site (which is awesome, I use it all the time) that I need to have a larger shell available for him to "move into". When should I have this new shell available for him and where can I find a suitable new shell? Also, how much larger should the new shell be? Thanks for any help you can provide. <A good idea to have a few "other" shells about for "up-sizing" all the time. To assure these are "marine safe" I suggest getting a few from your local fish store, or e-tailer... in an assortment of just barely larger on up to about twice the size your Hermit currently occupies. Bob Fenner> Theresa

Snail & Hermit Crab waste Hi Bob: My tank finally cycled with a lot of algae bloom. Two days ago I added 10 Scarlet Reef Hermits 10 Turbo/Margarita Snails and 30 Red Leg/Left-Handed Hermits from FFExpress. They have done an excellent job cleaning but I noticed a lot of waste since I added them in the tank. Is this bad for the tank? And should I pull out some of the hermit crabs out? <You neglect to mention how large your tank is. I would not use anymore than 1 hermit crab per 10 gallons. I use about 1 snail per 2-4 gallons depending on the tank, lights, etc.> Thank You, Aram <You are welcome. -Steven Pro>
Re: Snail & Hermit Crab waste
Hi Steve: I have a 54 gallon corner tank. I guess I should pull out some of the crabs and snails. What do you think? <Yes, I would remove all but two of each hermit crab. I would leave all the snails and if you need more algae eaters, get ten more Astrea, Cerith, or Nerites snails. I like to use a variety of snails as they all seem to prefer to eat different things. -Steven Pro>
Re: Snail & Hermit Crab waste
Thanks Steve, FFExpress should redo their Web Site about adding the correct amount of Invertebrates. ~Aram <Nothing in particular about FFExpress, but all of these places are in the business of selling. I never assume any salesperson, selling anything, knows everything about their product or wants to be my friend. Pet stores are all businesses, too. Just approach them as you should any business, as an educated consumer. -Steven Pro>

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