View Full Version : Crab came outta live rock....

12/20/2008, 04:51 PM
Hey all I'm new here so I'm gonna give you a little bit about my marine tank.

It's 33 Gallons, it has a half white sand, half argonite substrate. 9lbs of Live Rock (Two seperate pieces) and a bio wheel filter running at the moment.

As far as water levels go, everything has tested perfectly since the tank has cycled it's been up and running since October 6th 2008. I added the Live Rock on December 6th.

Anyway onto my question....I went to check on my fish as usual. I get these sudden weird feelings and I have to go make sure they are ok....if that sounds weird or not I don't care XD.

When I look at the base there is a random crab chillen...along the side of the glass. All the other times I'd checked I haven't seen him before and I didn't buy him haha, He must have hitchhiked on my LR.

That's why I'm here hoping I'm posting in the right place, hoping someone can help me figure out if he's safe to keep with my current fish.

Here is the picture: Crab O_o (http://smg.photobucket.com/albums/v494/xxmiddle_earth_Dreamsxx/?action=view&current=CrabO_O.jpg)

He has black pinschers his arms are off white, the top of him is light brown, where he is not brown on the top it's white. Then his legs are white with dark brown bands, his belly is white.

Current Residents:

1. False Percula Clownfish (Did have two but one jumped out)
2. FireFish Goby
3. (3) Hawiian Feather Duster Worms (On LR)
4. Evil Aiptasia Anemones (3 of them...very small, came on Live Rock)
5. Two Peppermint Shrimp (Put it to try to kill Aiptasia)
6. and this creepy crab XD

12/20/2008, 05:11 PM
I really hope some one can help....if not I'll take him to LFS next week and see if they can identify.

Jerry W
12/20/2008, 05:37 PM
I have two hitchhiker crabs that have been in my tank for years. Frankly, I never see them unless I move rock around, which is not often. Yours looks harmless to me. Actually one of mine is similar. My guess is it will spend most of it's time hiding and only come out to feed at night. Crabs are opportunisitc feeders and will go after any left over food or dead matter. If you notice snails or other crabs come up missing or dead, you might want to remove it, but IMO, it will make an interesting addition to your tank.

12/20/2008, 05:40 PM
Thanks so much. I'm just worried my fire fish has his little hide out in. I'm just worried the shrimp or the crab will get to him while he's resting but I'm sure he probably gets out of there fast enough.

12/20/2008, 05:41 PM
It looks like a sally lightfoot crab(?). I had one of those in my tank until my trigers got big enough to eat it. jt

12/21/2008, 07:28 AM
ehh I looked up pictures of them....they seem to be different.

Any more input from anyone on what this could be?

12/21/2008, 01:38 PM
It reminds me of porcelain crabs that hitched on my rock. If so, completely harmless and really interesting to watch.

Generally, in a fish only tank, the critter that needs to worry is the crab, not the fish! Your fish should be fine.

If its a porc. crab, it will have little feather like appendages in the front that it waves to catch microscopic food. Use a magnifying glass to watch, they are really kind of pretty. Considered reef safe and are good for clean up of the tank.

Mine got eaten by another common hitchhiker--Mantis Shrimp

Check out TampaBaySaltwater.com -- they sell live rock and have a page that describes hitchhikers.

12/21/2008, 01:49 PM
ok, just went to check out tampa bay myself

try this link


use the drop down menu to look at a pic of porcelain crab and also of gorilla crab.

you didn't say whether the crab in your tank is "hairy" If so, it could be a gorilla crab, as these have black tips on their claws. That would make it a more aggressive crab, and it may cause a problem for the peppermint shrimp. I don't think it would bother the fish, but I don't know that for sure, honestly.

Hope this helps

12/21/2008, 02:16 PM
Sorry about that, i think i mislabled him. Check this one out.

12/21/2008, 02:24 PM
In my experience, crabs are generally bad news, especially when they grow up. That doesn't look like a porcelain crab to me. I'd get it out of the tank. The black tips on the pincers are often associated with predatory crabs. Unless you can get a positive ID and determine, for sure, that it's harmless, I wouldn't risk the fish, your peppermint shrimp and feather dusters. JMO.

This is a digression, but... back in the day, in the 70s, when I first started keeping marine tanks, I found a cool looking crab at the Jersey shore. It looked pretty harmless (it was a decorator crab), then it ate ALL my fish! the spookiest thing about it was that I decided to keep it. I didn't have much money to buy more fish, so why not keep the crab? one day it was sitting in the tank, not moving, apparently dead. it creeped me out, and I threw it outside in the bushes. next day, there it was, in the tank. holy Night Gallery! turned out it left a very realistic looking shed exoskeleton in the tank. that nice meal of $50 fish must have made its old skin a little tight. :)

12/21/2008, 02:51 PM
Here is a thread my friend started in the local club. He had one that looks similiar to yours, and it turned out to be bad news. it ate a big purple tang, and a brand new blue spot jawfish. Attacked both fish while they slept.

UGLY CRAB (http://www.maast.org/forums/showthread.php?t=47607)

12/21/2008, 06:15 PM
<a href=showthread.php?s=&postid=13989601#post13989601 target=_blank>Originally posted</a> by jtscuba02
Sorry about that, i think i mislabled him. Check this one out.

I think that one might be it...but the only thing is his actual claws are black...do they vary?

12/21/2008, 06:24 PM
I am pretty sure none of the anemone crabs have black claw tips.

12/22/2008, 03:56 AM
I think it would be pretty hard to say a certain species looks exactly a certain way. Did it just molt, or maybe it is getting ready to molt? I know crabs will go thru color changes before the molt. Just like fish of the same species can have different coloring or patterns, maybe inverts do to.

Couldn't say if it would be harmful to your fish or not. I have had crabs in my tank when some of my fish were smaller, and had no problems. But when the triggers want crab for dinner, look out. jt