I really love the look of the halloween hermit crab but when I tried to buy one from my lfs, they told me that it wasn't reef safe. I always thought they were reef safe but I could be wrong. So I didn't purchase it but would like to get you guys opinions. Does it bother or kill corals or small fish? How's your experience with them in your reef tank if you have or had one in the past?
halloween hermit crab
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Rufus’ goofs
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All I can find as far as negatives is they get kinda big and can move around some corals and rocks, but nothing about eating them or fish. Maybe a large snail for a new shell though.
Perhaps others have some first hand experiences with these guys.
Perhaps others have some first hand experiences with these guys.
I have 2 and they never touch coral in my mixed reef. They are crabs and all crabs are opportunistic eaters that being said if you keep them well fed they may never look at your prized corals but at the same time they may decide to try something new. Best of luck I say go for it they are beautiful to look at.
Mikedawg
2500 Club Member
Mine is a perfect gentleman (except when he takes food from a coral) and I'm not aware of any downside other than the fact that they can bulldoze small pieces of rockwork if it isn't secured. Great scavengers (GHA, cyano, etc.) and add a unique color pattern. As for all hermits you'll want to keep a few extra shells in their tank to accommodate growth.
BTW, did you LFS give you a reason they are not considered reef safe?
The Reef Dork
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Same story with me - they're just not snail safe. Pulled a conch out within minutes of the conch being added. Had to sump then re-home him for attempted murder 
Will_WhatIsThis
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I know I’m 2 years late but I figure people still read these and could still get some info from this. I had a Holloween and it was a model citizen. It never killed any snails (I have nassarius snails and trochus snails. I don’t know if hermits don’t like those snails but still). He never ate any coral. He was always busy eating little bits off the rocks. Maybe I got lucky, but from what I saw it was an amazing addition. I put it in and never had to worry about it doing anything bad. Every critter is different I guess.
Saltyanimals
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never too late to revive old threads as these things serve as a history for all future reefers. =)
+1 to many other comments here. Completely reef safe for mine. never touched coral or anything else that I'm aware of. I did lose mine a couple days again hence the post here while I was searching for average life expectancy of these things. No real known cause of death maybe simply of old age. I had him for 3-4 years which his shorter than what I've read on wiki, but then again we're talking home aquariums here. Will replace w/ another one soon.
+1 to many other comments here. Completely reef safe for mine. never touched coral or anything else that I'm aware of. I did lose mine a couple days again hence the post here while I was searching for average life expectancy of these things. No real known cause of death maybe simply of old age. I had him for 3-4 years which his shorter than what I've read on wiki, but then again we're talking home aquariums here. Will replace w/ another one soon.
Phycodurus
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+1 on possible attack on a conch. found one of my halloween hermits wearing a conch shell. ;Dead
i can only suspect that the hermit killed the conch for its shell (despite having some similar-sized empty turbo & trochus shells laying around the sand bed here and there). i have to acknowledge the possibility that the conch just up & died. i bought a trio on conch snails, and the other two are still out & about. the hermit is very endearing to watch, but i pulled him out.
i can only suspect that the hermit killed the conch for its shell (despite having some similar-sized empty turbo & trochus shells laying around the sand bed here and there). i have to acknowledge the possibility that the conch just up & died. i bought a trio on conch snails, and the other two are still out & about. the hermit is very endearing to watch, but i pulled him out.
I was under the impression that Halloween crabs only lived in conch shells. Mine has been in the tank 1.5 years and doesn't touch the corals at all. I do blame it for the decimation of all of my hermit crabs though. I had 10 at one point and 8 months later I have only the Halloween left. My snails seem to be okay though. I'm sure its eaten a few of them but its a good excuse to go to the LFS 
Halloween hermit crabs, Ciliopagurus sp., specialize in living in flat conical and long shaped shells. Most commonly this includes cowrie (when the hermits are young and small) and cone snails - occasionally conchs. I think they may occasionally inhabit triton shells, but this isn't common in the wild. Species in the genus Dardanus and Calcinus tend to inhabit triton shells, hence why you won't often find them in these shells and they don't have a high preference for them. They will probably never try on a turbo or trochus shell unless it was forced to, crabs will take anything as shells when required - I have seen some Calcinus pictus take up vermetid snail shells before. The turbo and trochus shells are essentially useless to the Halloween hermit crab because it isn't the right shape. They have flat bodies, so they need flat shells. If you don't give hermit crabs adequate homes, don't blame them for acting out. On the other hand, the Halloween hermit crab is one of the slowest and docile hermit crabs I've ever kept. I've kept many before, and I have not had any attack hermit crabs. They are simply too slow and awkward, their claws are also not in an aggressive shape that is good at killing hermit crabs. For @HockeyRooster I want to clarify if the halloween hermit crab you have is a Calcinus pictus or Ciliopagurus sp? Calcinus pictus is very aggressive and could very well kill a bunch of hermits, while Ciliopagurus would not. It is more likely that the hermit crabs all killed eachother off, but did not bother to kill the Ciliopagurus because their not conspecific and nor do they have similar behavior and shape.I was under the impression that Halloween crabs only lived in conch shells. Mine has been in the tank 1.5 years and doesn't touch the corals at all. I do blame it for the decimation of all of my hermit crabs though. I had 10 at one point and 8 months later I have only the Halloween left. My snails seem to be okay though. I'm sure its eaten a few of them but its a good excuse to go to the LFS
To answer OP, from my experience it is reef safe and fish safe. They don't go after snails, except perhaps any snails that are the shape it would want to inhabit - conchs for example. I have never had a problem with them attacking Trochus snails - unlike other types of hermit crabs. You need to add cone shells/conch shells that it can grow into. Normal shells will not do. I have even kept them with pretty sessile fish like a baby frogfish before. The frogfish hardly moved at all, and yet the halloween hermit crab that was much larger than it did not ever touch it.
waterskiguy
Active Member
I've had a couple in my tank for the last couple years and they've never bothered anything that has been noticeable. They're slow moving, awkward and very uncoordinated so they're really fun to watch shudder along the sand bed and climb up the rocks like a 1 legged, 1 armed, 3 toe sloth.
Saltyanimals
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Piling back on to my earlier response that mine hasn’t touched a single thing in the tank that I’m aware simply bc it has the same shell since I bought it.
I will say that my earlier comment about dead Halloween fortunately was wrong. I thought he was as dead since he didn’t move with arms and everything hanging out, but eventually moved and was alive after all.
Now this leads to my next questions.
I’ve never provided him additional shells and I’ve had him now about 5 years. He doesn’t look like he’s too big inside the shell but I’m not a hermit crab. How are everyone else’s? How often do you prove shells Are they fully hidden inside the shell as mine is not.
I will say that my earlier comment about dead Halloween fortunately was wrong. I thought he was as dead since he didn’t move with arms and everything hanging out, but eventually moved and was alive after all.
Now this leads to my next questions.
I’ve never provided him additional shells and I’ve had him now about 5 years. He doesn’t look like he’s too big inside the shell but I’m not a hermit crab. How are everyone else’s? How often do you prove shells Are they fully hidden inside the shell as mine is not.
@HockeyRooster I want to clarify if the halloween hermit crab you have is a Calcinus pictus or Ciliopagurus sp? Calcinus pictus is very aggressive and could very well kill a bunch of hermits, while Ciliopagurus would not. It is more likely that the hermit crabs all killed eachother off, but did not bother to kill the Ciliopagurus because their not conspecific and nor do they have similar behavior and shape.
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You clearly know more than me about the Halloween hermits so if you say they don’t eat other hermits I believe you. I don’t know which Halloween I have-bought it at LFS as a Halloween. My statement was purely anecdotal. Halloween in, slowly the rest of the hermits died. Most of the snails lived though. I have several conch shells and my Halloween has tried them all and settled on the medium one. I do provide shells for the hermits too. I just added 6 more small blue leg hermits and will watch them.
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You clearly know more than me about the Halloween hermits so if you say they don’t eat other hermits I believe you. I don’t know which Halloween I have-bought it at LFS as a Halloween. My statement was purely anecdotal. Halloween in, slowly the rest of the hermits died. Most of the snails lived though. I have several conch shells and my Halloween has tried them all and settled on the medium one. I do provide shells for the hermits too. I just added 6 more small blue leg hermits and will watch them.
You clearly know more than me about the Halloween hermits so if you say they don’t eat other hermits I believe you. I don’t know which Halloween I have-bought it at LFS as a Halloween. My statement was purely anecdotal. Halloween in, slowly the rest of the hermits died. Most of the snails lived though. I have several conch shells and my Halloween has tried them all and settled on the medium one. I do provide shells for the hermits too. I just added 6 more small blue leg hermits and will watch them.
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The comment about the turbo and trochus snails was directed at the other poster.
Remember to use your own discretion for things like this, each individual varies and could have drastically different behavior - so just keep your eyes open like you said you already are.
Phycodurus
Well-Known Member
*very* interesting point ... i never thought past “a shell is a shell.” looks like i’ll be on the lookout for empty conch & cone shells, and then give the halloween hermits a second try. ;Bookworm
bee_holes
New Member
Late thread but figured I'd add my own experiences.
My Halloween hermits are beautiful, but have killed and eaten a ton of my other snails, hermits, and my tuxedo urchin. This included a lot of trochus and nassarius snails I had- and trust me I had plenty of shells and other food sources for them.
Them eating my urchin is the last straw for me. I've loved hermits since I was a little kid. It's hard trying to keep these IMO when they are very efficient at decimating my clean up crew in my relative small tank (50 gal). No issues with fish or corals though
My Halloween hermits are beautiful, but have killed and eaten a ton of my other snails, hermits, and my tuxedo urchin. This included a lot of trochus and nassarius snails I had- and trust me I had plenty of shells and other food sources for them.
Them eating my urchin is the last straw for me. I've loved hermits since I was a little kid. It's hard trying to keep these IMO when they are very efficient at decimating my clean up crew in my relative small tank (50 gal). No issues with fish or corals though
Exactly my experience, asked here a while ago was my urchin safe as I saw the Halloween on his back a few times, the answer was yes, turns out that was wrong…mine is definitely not clean up crew safe and the jury is still out if he also ate my torch and hammer as he was seen on top of those before they died, clearly eaten by either the Halloween crab or my previous peppermint shrimp, the peppermint is now dead, my new torch is still alive so can’t blame the Halloween on the coral deaths YET.
