ReefCleaners micro decorator crab info thread

[Tired]

Important update: these do snip zoanthids to wear, once they get to about a carapace the size of a dime. They look like they have about nickel-sized carapace at this point due to water magnifying things. Mine has only taken a couple at a time. Will update with if the zoas it wears actually survive, because if they do, the crab's shed carapace would eventually just become a new frag.

 

Update: I got one. I'll list what happens in here. 

Update: the prior one died of unknown causes awhile ago, possibly due to not having molted for several months. Excessive hair algae on its back may have interfered with this, or there could have been an iodine level issue- I didn't check at the time. It was also about full-size for the species, I think, so it may just have been old. Nothing else in the tank was in visible distress at the time. I have two smaller ones now.

 

Pros so far: 

VERY cool little animal. Watching it build a disguise is on par with watching a pistol shrimp burrow. Fun to watch in general. 

Unique-looking crab, fun shapes. Something about the "costume" is charming as all heck. 

Get to show it to guests by saying "hey, find the crab" and watching them not find it until you point it out.

Not aggressive.

Picks at turf algae pretty enthusiastically, to eat and not just to wear. 

Small bio-load due to size. 

Due to its disguise, seems to stay out in the open. Hard to spot, but out there, not crammed into a crevice somewhere.

Wanders around the tank, returning to predictable spots. Not overly active, but moves around. 

Very unlikely to harm any animals larger than an amphipod.

Will possibly disperse neat sponges around your tank, if it comes in with them.

Can evidently be kept with others of its species.

Cleans macroalgae reasonably well of microalgae.

Fun to try to spot it once it's disguised. 

Summary: tiny, neat crab, may be reef-safe? Won't eat your corals, at least. Might poke them. Great fun to watch. Multiples probably work fine. Cleans algae from macros.

 

Cons so far;

May stand on your corals for awhile and minorly bother them. 

Will wear small zoanthids it finds loose or can easily dislodge, though bad at this.

Will tear up delicate macros to wear. 

Is now wearing Caulerpa verticillata around and thus will probably spread it more than I had particularly wanted, will undoubtedly do the same with other things. 

Update: will also wear hair algae and cyano.

Small, easily predated upon.

You are not gonna find this thing in a non-nano. Probably best in a pico.

Summary: it's still a decorator crab, even if small. It's also very easily eaten, and would vanish in a larger tank. Might spread unwanted algae around, though will also eat it. 

 

 

Notes: 

Will wear zoanthids if it finds them loose, seems unable to pry them loose on its own. Same for pineapple sponges. Doesn't seem interested in calcified macros. Will wear softer macros, any algae it can pick up, and cyanobacteria. Seems uninterested in wearing inanimate objects. 

Will quickly get used to disturbances if the disturbance is minor, i.e. the shadow of a removed lid passing over it. Takes longer to get used to a human moving near the tank, but also gets used to that.

Picks at algae and detritus to eat.

Looked excited when I poured some frozen food near it, but didn't catch any. Update: can be taught to eat from pipette or tweezers. Will get very excited about anything you do if trained to eat from tweezers. 

Ran a claw over its back when the food touched it. I saw a video of a similar species (or possibly this one) catching and eating an amphipod off its back, and I rather suspect this would also do that. Though it's not an active hunter, so all it would catch would be any that bumped into it. 

A hermit crab stepped on it, and started poking at it like it was sand. It responded by kind of pushing upward, then poking at the hermit with a claw, and the hermit backed off. I wouldn't put them with anything super aggressive, this was just a scarlet reef hermit (very docile), but apparently other animals don't notice them any.

Actually moves pretty fast when startled, and holds VERY tightly to rockwork. Cannot be easily pried off by hand.

Clumsy. No swimming ability whatsoever- fell on its back when gently added to the tank. Righted itself fine, but awkwardly. 

When I first got him, I put him in a dish with some macros. He wouldn't touch them, but started trying to escape. When I put him into the actual tank, and he put himself against the rock, he calmed down immediately. 

 

 

 

Have some pics. First two are when I'd just got it and it wasn't decorated yet. The second-to-last pic is shortly before it got stepped on by a hermit that I'm certain thought it was just sand. I've never seen a hermit crab look so startled as when the decorator poked it. 

 

 

 

Old post below. 

 

Quote

I really like the looks of the micro decorator crab that

@johnmaloney sells, but I can't find much info online, so I'm looking for some personal experience from different people who've kept them. 

 

How big do these get? Carapace and leg size, or an estimate. Is "micro" just compared to other decorators, or do they actually stay tiny? Porcelain-sized? 

Are they at all aggressive to anything? 

Do they move around much, or just pick a favorite spot? 

Will they leave LPS and rock flower anemones alone? 

Do they eat anything other than algae? 

They can't climb glass, right? 

 

I know they'll sometimes decorate with zoas, here's a few questions about that.

Do they tend to remove the polyp intact? 

Do the zoas have a good chance of surviving on the crab? 

Do they ever drop the zoas? 

Do they just take one polyp from the colony, or do they tear up the whole thing? 

Do they primarily stick to macroalgae if offered plenty of that to use? 

Does the ratio of macroalgae to zoas in the tank affect what they want to use as camo?

[billygoat]

I kept a few of these crabs for several months in my 18g aquarium. Eventually they ended up vanishing (I think they were probably eaten by my large brittle star), but I did make some observations about them while I had them.

 

 

These decorators are quite small. Not sure about maximum size, but mine were no larger than a nickel from leg-tip to leg-tip, with a carapace about the size of a dime. They demonstrated no interest in any of my other livestock, zoanthids included, but did pick algae off the rocks and decorate themselves with it prolifically. I imagine that they would be happy to decorate themselves with whatever they can pry off the rock, but their claws are extremely small so it's unlikely that they are capable of shredding up zoas or other invertebrates. Can't imagine they'd have much interest in LPS or rock flowers either, but they would occasionally climb my gorgonians (with no harm done to the gorgs). They move more than I expected them to, though they did seem to choose a "territory" and stay within its boundaries most of the time. They are probably omnivores but primarily eat algae, after the manner of most hermit crabs. I found them to be fairly effective cleaners for certain types of hair and turf algae. They are incapable of climbing glass or other smooth surfaces, and spend almost all of their time on the rocks. Overall I'd say they make for an interesting and quite harmless addition that will do well in most nano aquariums.

 

Hope this is helpful! 😊

[Tired]

That's good to know. I have some really small zoas (the whole polyp is maybe a quarter inch tall), but I wouldn't mind a decorator picking up a couple of polyps. I'm thinking I could put any single-polyp frags on a magrock or such where the crab couldn't reach, and only put them in crab range once they had more than one polyp. That way the colony will be, at worst, inconvenienced.

 

Plus, I've found pics of decorators with perfectly happy zoas on them. I figure either they'd shed the shell eventually and I could put it in the light, or they'd shed and transfer the zoas, and then they'd stay on the crab. 

[Tired]

Came back from a 5-day vacation to find that, 1, I had a little algae bloom while I was gone. Everything's fine as far as I can tell, but maybe a snail died, or maybe it's just from this being a new tank. And, 2, Sandman shucked off all the caulerpa (I don't think he molted because the sponge is still on him) and now has a lovely coat of, mostly, slime. I ASSUME he's put it on himself on purpose. Surely he'd clean it off if he didn't want it on him. That speckled sponge on his back also seems to be growing, which is cool. I guess this is what he thought would help him hide the best. Which, yeah, he blends in pretty well now. I'll give him that. 

He's also decided that he likes this spot. It's where he hangs out now. He fits very nicely. I'll have to be sure not to cover up that spot in future so he can keep his spot.

[Tired]

Update: he's finally put some zoanthids on!

The smallest ones I have. 

Those are tiny zoas. The biggest ones below him aren't even a quarter-inch wide. He picked the very smallest of them, 1/8" at most, and probably from a patch that was kinda loosely attached anyway. This rock has a lot that aren't anchored very well. He's been redoing his disguise, so I'm curious if he'll pick up more of these zoas and start hanging out in this spot, or what he'll do. 

So, he'll pick up zoas, but barely. Hasn't touched any of the normal-sized ones. I also notice that the polyps he did pick up don't seem too bothered. One is mostly open (and a lot of these only mostly open anyway, they're fussy), and one is a bit scrunched, but appears to be doing that only because it's being touched. It'll probably get used to that and open up. 

 

I'm not sure how big this little guy is gonna get. If he stays this size or so, I'd call him reef-safe, since he's evidently fine for all but the very smallest zoa polyps. So far the only things he's really bothered have been things he's walked on. 

 

I've pipetted him clean several times now, but scraps of the cyano cling on and grow, and I think he's finding more somewhere. He's definitely wearing that stuff on purpose. At this point I'm letting him keep it, just cleaning that tiny patch of pink-spotted sponge now and then. I like that stuff, and hope to keep it when he eventually molts. 

 

I find it interesting that he's covered his legs so heavily in algae. It does a good job of breaking up his shape, which is probably why he does that. I imagine it's partly also because that's where he can most easily reach, though.

[Nano sapiens]

Good info.!  I was eyeing these the other day as possible additions to my nano.

[Bailyfox]

I'm definitely interested in getting one of these guys once my future coral and macros are settled in and doing well, such cool creatures.

[Tired]

I'd say go for it! Mine hasn't caused any trouble so far. I'm not really feeding the tank, but it seems to be finding plenty to keep it fed. I can't say for certain it won't bother anything, but it doesn't seem to have the claws to harm much of anything, or the inclination to do so. And, c'mon, it's a nano-sized decorator crab. Who wouldn't want one? 

 

Heck, my scarlet reef hermits are more trouble than this. At least he hasn't knocked anything over that I'm aware of.

[A.m.P]

Very cool thread, hope to see more updates on the little chap, been considering grabbing one myself for quite a while. Not the season for it now though haha.

[Nano sapiens]

4 minutes ago, Amphrites said:

Very cool thread, hope to see more updates on the little chap, been considering grabbing one myself for quite a while. Not the season for it now though haha.

My thoughts, too, and would wait for late spring.

 

I wonder what the expected lifespan would be?  Crabs tend to last longer than shrimp, so if these little guys can go maybe 5+ years or so like a hermit crab, that would be nice.

 

[Tired]

Well, he was $5 from ReefCleaners. Even with shipping factored in, it's not quite a $20 critter. I'll be perfectly happy if I get just a couple years out of him, though I would of course prefer more. About the only downside is that reordering might be a little tricky, since you have to wait for a tiny creature that makes its living off of Not Being Found to be found.

[Tired]

Had to move him out of the way to shift some rocks around, and I thought an updated shot of just him would be fun. He's got such short little hindlegs. He also continues to be very aware of his surroundings, which is interesting. He was on a small rock, and I put the whole thing in this container with some water. He immediately crawled off the rock and started looking for a way out of the container, instead of staying on the rock to hide.

 

I've continued to be fascinated by this little creature. He's self-aware enough to somehow know what he looks like, including on his own back. Can he see parts of his own back, maybe? I wonder. And he can then compare himself to his environment, and figure out what he should wear in order to properly blend in. He's aware enough to continue making assessments and change his costume if need be, which is really interesting.

[Tired]

So, yesterday one of my rock flower anemones went and parked itself on one of Sandman’s perching spots.

Apparently he is both fine with this and RFA-proof.

I gently bothered the anemone so it would retract a bit and I could check that it’s not actually holding the crab. It doesn’t seem to be.

[Tired]

Update: these are about 99% reef safe. 

She snipped a couple of tentacles off of a long-tentacled palythoas polyp, I guess to try and use as decoration. It didn't work, and she's left the palys alone since then. It didn't do any real damage to the polyp, it's just a little lopsided now. Absolutely worth this cool little creature.

 

Also, this is a lady decorator crab. Inadvertently saw her underside while transferring things to a new tank (clumsy crab + gentle pour from a cup = temporarily upturned crab), and the little curled-up tail is a U instead of a V, which usually means female crab. The name stays, though, as this is a crab and has no concept of gender, or any ability to be offended by being called any sort of name. 

[Tired]

Update: uuh

I assume she's fine. I've seen her grooming her face to keep her eyes clear. Reasonably, if she didn't want that much on her, she'd snip it away. 

Answer to the un-asked question of "will hair algae grow on a decorator crab" is a resounding YES. It's interesting- she actually sticks out more like that, now that I know what to look for. You'd never know that there was a crab under there from most angles, but I'm just looking at this one patch of hair algae wandering around in there, in a tank that has basically no other hair algae, and, yeah. She stands out a little. 

I think she fends off the amphipods that might otherwise eat the hair algae. She doesn't seem to like them any- it's the only thing I've seen her be aggressive at. Waves her little claws at them when they get too close. To be fair, they do try to steal her food.

[Nano sapiens]

You could help her out and trim that hot mess...how about a mohawk 😏

[Tired]

I considered it, but I'm sort of curious if she'll eventually trim it herself. She doesn't seem particularly hindered. I'll definitely help out if it starts to be a problem, but I'm inclined for now to let her keep the absurd amount of fuzz.

[Tired]

These little dudes are in stock at ReefCleaners, if anyone wants one. They apparently sell out quick, though. 

 

If you get one, feel free to comment here with any observations, since this is literally the only site other than the seller that has any info on them.

[CD_Scapes]

13 minutes ago, Tired said:

These little dudes are in stock at ReefCleaners, if anyone wants one. They apparently sell out quick, though. 

 

If you get one, feel free to comment here with any observations, since this is literally the only site other than the seller that has any info on them.

Guess who just got 5 of them And macros for them 😁

[Tired]

Oh, nice. Could you watch, specifically, to see if they interact with each other much? I'm curious if they're at all social, or if they're like turtles, and just ignore each other.

[CD_Scapes]

Just now, Tired said:

Oh, nice. Could you watch, specifically, to see if they interact with each other much? I'm curious if they're at all social, or if they're like turtles, and just ignore each other.

Will do, should be easy in the 7 gallon...eventually moving to a 12 so I might get more closer to the move day

[growsomething]

Also recieved the notification from reefcleaners.  I'm afraid my emerald crab might eat them.  Any idea if he would?

[Tired]

I'd look up whether emerald crabs attack porcelain crabs, that should tell you a bit. I don't remember how mean they tend to be to similar animals. I know the bigger emeralds can be pretty aggressive towards each other, and I believe sometimes to other crabs. Might not be best to mix them. The decorators have pretty tiny claws, they wouldn't be able to defend themselves. Though- the emerald might not even see one. My hermits would walk right over the poor thing. 

[growsomething]

12 hours ago, Tired said:

I'd look up whether emerald crabs attack porcelain crabs, that should tell you a bit. I don't remember how mean they tend to be to similar animals. I know the bigger emeralds can be pretty aggressive towards each other, and I believe sometimes to other crabs. Might not be best to mix them. The decorators have pretty tiny claws, they wouldn't be able to defend themselves. Though- the emerald might not even see one. My hermits would walk right over the poor thing. 

I could only find ppl saying they keep both porcelain and emeralds together okay, so I ordered 3 for the 10g, although they are much smaller crabs.  Maybe I'll take the emerald back to the lfs.  Thought I got the last ones, then this morning 68 are listed for sale on reefkeepers 😛

[CD_Scapes]

1 hour ago, growsomething said:

I could only find ppl saying they keep both porcelain and emeralds together okay, so I ordered 3 for the 10g, although they are much smaller crabs.  Maybe I'll take the emerald back to the lfs.  Thought I got the last ones, then this morning 68 are listed for sale on reefkeepers 😛

Time to buy all of them 😂