Good or Bad Crab?

[Iphis]

Dude, that is an awesome picture.

Mine is definately not one of those, unless they change a bit during their growth... The shell is too rounded and his eyes are too close together. (Always the sign of a shifty one)

Mine all have very flat bodies. Plus the claws are definately not that beefy, very long and slender. At least now I know mine is not a red mithrax

Either way, they're not eating sponges or corals.

Speaking of, this morning I caught my first glimpse of my mantis head in the tank.

Only reason I want him out of there is so that he will leave my cerinths alone.

He is so freaking cool looking. A bright, florescent green.

Either way, Phil, your crab looks very cute. Do you have a sump you can put him into, at least? I feel bad him being out of the tank like that

Oh, btw, FSW....

The hermits and things tend to avoid places with cyano. If you notice something that looks like reddish saran wrap that may have bubbles trapped in it, get a turkey baster and blow it away. It is generally poisonous to herbavores so they leave it alone, from what I've read.

How is your last shrimp doing?

I got two with my package, was only expecting one. One of them has molted and is currently hiding in the rock, the other zooms around the tank all day. Highly amusing.

 

[FW2SW2004]

Didn't see my last shrimp last night, but my attention was focused on another big hairy crab...just like the first one I posted in this thread...doesn't resemble any of your crab pics...I am pretty sure he is a Gorilla crab and managed to catch him but not his smaller counterpart. Hairy legs and body...pointed claws that are dark red...not quite black but close.

In the process of catching my hairy crab. I had a small catastrophe with my pink tipped anemone TBS sent with the order. It was nestled on the rock I moved to access the crab then retreated to the back of the tank and got sucked into my cannister filter intake screen.

When I noticed what had happened to it I immediately turned off the cannister removed the anemone and it looked very tiny with only little appendages...I thought they had been sucked off by the filter.

Later I came to check on my anemone and his appendages had started to fill back out.

Never having a salt water aquarium this is all new to me. I thought I had killed my anemone or at least decapitated him for life until he could grow out more...but I guess they can shrink and fill back out pretty quickly. I am anxious to get home tonight and check on it....it was really fun to watch it move around the Live Rock...it was always searching for a better home than where I had placed it.

My three year old daughter was distraut with the possible death of the anemone.

 

[patsan]

Phil,

Does it look like this?

That's my porcelain crab.

Here was my gorilla:

 

[phil519]

Pat - No - while the crab has similar white markings as your porcelain it never once displayed the filter feeding appendages while in the main tank (whereas the other porcelains I have do). Also the porcelains have that very long antennae (at least the one's i've caught). This crab doesn't have those characteristics.

iphis - yes i do have a sump - he's still fine in his cup this morning but i may dump him in the sump temporarily. Good luck with your mantis! I hear clicks in my tank but am led to believe that maybe I have a pistol rather than a mantis (no deaths - plenty of live barnacle targets untouched), 2 months and counting.

FWS - cyano dislikes strong water flow - try adjusting your PH to improve the flow in your tank. Oh anemones can recover from being sucked into an intake - but they require some monitoring. Condi's are pretty common in the TBS package - hopefully I can get one too!

 

[FW2SW2004]

Patsan

Patsan

Mine looks like your gorilla only the claws are not quite as black...more deep red.

No sump...so I will sacrifice.

I hear some clicks too....last time...it was a mantis but I didn't see him for about 3 weeks...then was lucky enough to catch him and get him to my LFS where the Trigger had a snack...circle of life you know.

I may watch my smaller crab grow and see if he causes problems. Still no fish so I am not sure I would know if he is really a bad crab or not...I will monitor the LR growth for possible signs of damage I guess.

What do these so called bad crabs do?

 

[patsan]

eat fish, corals, sponges and destroy lots of stuff in the tank.

 

[phil519]

No matter what label you give a crab - it is an opportunistic omnivore. This means that the so-called "algae-hair" eating crabs will sometimes take a snack or two of meaty-food if the opportunity arose. Same for the filter-feeding poreclain crabs - I would imagine if the opportunity arose (sick fish swimming meekly by) - it might take it.

In a diverse ecosystem with healthy critters though - theoretically the crab will behave - but who knows!

Oh and besides the list pat gave - I've heard of crabs slicing up healthy serpent stars/brittle stars for snacks.

p.s. some crabs - like a decorator just like to tear things down and put them on their back. It's amusing I guess - until your favorite coral becomes wall paper for a crab.

 

[Hooked on Salt]

I have a hermit crab that likes to pick/eat pieces off the tube on my feather duster!

 

[Hooked on Salt]

caught him - here's a pic...

Is this a red emerald?

I don't know the name of these either but I have a ton of them in various sizes in my tank. They were all hh on my TBS rock. They don't seem to be eating anything but algae for now. Time will tell though....

 

[Iphis]

Heh. Hermit crabs tick me off.

I have one that was a hitchiker with the rock, he's very well behaved. Very amusing little dude. Just sits there picking up pieces of live rock all day. He lives in a cerinth shell that came with the live rock and was dead since day one. Was too big for him when he moved in, couldn't even move it around. Now he gets around fine. He is all brown with little blue shoulders. Those two little blue spots are the only color on him.

This hermit crab is cool.

However, when I added the 20 or so hermit crabs that came with the second part of the package are all brightly colored and very pretty with their oranges, yellows and blues. However, they get into everything. They keep attacking my snails, my nice hermit crab, my porcelain crabs, and my tubeworms.

One little hermit crab ran into the hole with the mantis shrimp, I saw his shell come rolling out after a loud click, he put out his claws, then before I could blink the mantis shrimp was all over him. Best I could tell is he is a goner. His shell was dragged into the hole.

They're my biggest problem people right now. I have several "gorrilla" crabs, 3 known supposed "Red Emerald Mithrax", a mantis shrimp and a plethora of porcelain crabs.

I have to pull the little guys off everything.

I'm upgrading to a large cube tank this weekend, so I'm hoping they will be more docile when they're spread out a bit more.

Iphis

 

[phil519]

I re-looked at the TBS site where it lists good/bad crabs and I tried to look at the "bad" crab on the top. Here's a photoshop pic of it...

It does have a resemblance to the crab in my pic.

 

[H2OLUVSME]

it does have a resmablance phil, hmmm...

i wish i could help with an id there. one thing id like to point out about a few comments made. phil is correct in his assumption about all crabs are only partly "reef safe". they will eat anything. i dont really see a porcelin catching a sickly fish though. even though their claws are huge, they are paper thin and worthless for capturing prey. they will however grab small meaty food with them and stuff their face.

i have a red mithrax in my mantis tank, because he was eating zooanthids. i think its a case by case scenario, and i think the crabs can flip at any time. most of the "herbivorous" crabs (i dont think there is such a thing) will eat anything when they run out of algae, including serpent/brittle stars, small fish, corals, my prized cleaner shrimp arghhhh!!

FSW - i think you are wise to sacrifice.

Phil - id keep him in the sump until you get a positive id. maybe put a little rock in there and see what he eats off of it.

 

[phil519]

Agreed! As an aside I was cleaning my tank and I accidentally knocked over a small baseball sized piece of LR that I had "set" on top of some larger LR. What do I spot - my big porcelain crab! Unfortunately my action of knocking over the baseball must have somehow clipped him and he was cut in 2. At that point he was maroon clown food. RIP.

Anyway - here's Dr. Ron's take on my small crab:
Hi,

It is possibly a small Mithrax pilosus, however such identifications of juvenile crabs are difficult. Good luck if you want to keep it; personally, I think that is asking for trouble. Most small crabs are generalized predators and will eat whatever they can catch.


__________________
Cheers, Ron

 

[elises]

the bad ones always look so cute though.... well sometimes.. makes me wanna setup another tank for them! ;[

 

[liverock]

Re: Lost Peppermint Shrimp

Re: Lost Peppermint Shrimp

Well, here is an update on my TBS Package.

Second half went in 7 days ago.

TBS sent me 3 Peppermint Shrimp and to date I have seen evidence that two have been murdered. I have no ID on any definite suspects yet, but I suspect there may be another Mantis Shrimp who came in with the second half of my package...only a few clicks heard so far ...or...I have also seen what looks like another "Gorilla?" crab like the first one I started this post with.

Could this Crab be eating my Shrimp?

Their bodies are usually seen on one side of the tank bottom split in half...then by the next morning they are gone, but I suspect the clean up crew is just doing its job.

I also have a purplish slime algae in spots on the sand bed...is this cyano? should I remove it...or let the hermits, snails, brittle star, shrimp try to munch it up?

I"ll bet the pep shrimp molted.....as when you find an empty shell split in the middle...is a molt.....shrimp usually do that when shipped and introduced into a new tank...
TBS