Just found 2 crabs in my tank

[Kgrizzle]

I just spotted them when feeding my coral and trying to trap the biggest fire worm and I seen a claw come out of a hole in the live rock then while staring some more at the tank I seen another bit of movement and with a flash light low and behold another crab... The first one is buggin me a little cause i think he might have bit my coral but am not sure... Looks like a little chuck smaller than a match head is broken off the edge

[Kgrizzle]

I can see the ones legs and they are black and white stripes by the looks of it... Can't see much else

[Madreefer]

Put an uncooked shrimp in a tall drinking glass after lights out. Put it in at a bit of an angle. Crab goes in and cant climb back out. For the worm put the same bait in a peice of pantyhose.

[Kgrizzle]

Awesome was trying to use a Baster to get them

[gregzz4]

Put an uncooked shrimp in a tall drinking glass after lights out. Put it in at a bit of an angle. Crab goes in and cant climb back out. For the worm put the same bait in a peice of pantyhose.
Nice tricks, I'll have to remember those

And better finding crabs in your tank than elsewhere :mrgreen:

[Kgrizzle]

Hahha yes definetly ... Is it possible he tried to eat the coral?... And if I have 2 and they go in the same glass will they fight?

[toytech]

If there not too close to your coral you can fill a turkey baster with boiling water(be careful ) and blast the hole with water. Crab legs anyone? I found a rock crab on the weekend and took the end of my alge scraper and smashed the sucker into a paste .

[Nano]

if you catch them post some pics! I always love seeing hitch hiker crabs, as long as they aren't in my tank :lol:

[Kgrizzle]

Lol I guess I shouldn't worry if they fight eh not like they cost anything but still wouldn't mind trying to keep them... Oddly enough they survived a 20 min car ride with out water

[Nano]

if they turn out to be "not reef safe" (what crab is right) I would throw them in the sump then they can keep live rock clean

[Kgrizzle]

Good call I only have a canister filter but still he can keep that rock clean

[paddyob]

Lol I guess I shouldn't worry if they fight eh not like they cost anything but still wouldn't mind trying to keep them... Oddly enough they survived a 20 min car ride with out water



Bad idea all around. Most hitch hiker crabs are predators. Unless you can 100% ident them... Flush them or feed a hungry trigger.

Lots survives on live rock. Live rock is shipped internationally wet but not in water.... Imagine the weight of 1000 lbs of rock IN water.

20 minute car ride is nothing.

Good luck.

[Kgrizzle]

Fair enough... I'll have to stop by the grocery store and grab some u cooked shrimp

[Nano]

yeah I have to agree I would try to keep them out of your tank, the sump is ok I think. but keep them away from you display, you never know they might grab a fish for a snack at night or coral..

[Aquattro]

if they turn out to be "not reef safe" (what crab is right) I would throw them in the sump then they can keep live rock clean

Unless I have a crab living in a coral and doing damage, I almost never remove them. Unless they're big, or you have really small fish, they're all mostly fine. My rule is unless they do something bad, they get to stay.

[Kgrizzle]

Ya don't have fish yet ... Still doing the initial cycle it's the corals I'm worried about cause it looks like he might have nipped my chalice a little bit... Any other baits I could use

[Nano]

lol good rule, my emerald crab is going to be getting banished to the sump once I upgrade my tank, he likes to taste my Zoanthids. :sad:

[Nano]

shrimp will work for sure. I put shrimp in a net and left it for 20 minutes and pulled out a 3 inch bristle worm!! I put him back but its was neat

[Kgrizzle]

Ya I like that rule to it makes complete sense ... Let nature do its thing and u see something corrupting ur peaceful and tranquil harmony remove it

As for the shrimp, do u think think mysis in the pantyhose will work?... I'm debatable whether to keep them or not... I just don't like the look of it... I know they are good cleaners but not pleasant looking

[Nano]

yes mysis works, everytime I feed my blenny my crabs and bristle worms come out to eat too

[naesco]

Unless I have a crab living in a coral and doing damage, I almost never remove them. Unless they're big, or you have really small fish, they're all mostly fine. My rule is unless they do something bad, they get to stay.


I have been reefing for for 20 years and have never seen a crab attack a coral or fish.
They might I guess if you do not feed them. Drop a pellet in their direction from time to time.

I agree they are completely fine in your tank.

[Kgrizzle]

Stow away number 1
http://img.tapatalk.com/464b5e07-36fb-3369.jpg

Second stow away
http://img.tapatalk.com/464b5e07-371f-1749.jpg

[Kgrizzle]

Help I'd?

[mike31154]

I've had up to 4 in my display. A couple have since disappeared & I had to dispose of another several weeks ago. Caught him red handed with a piece of ricordia coral that I think he removed from the rock, frag plug & all. Pretty sure it was a Xanthidae, Actaeodes tomentosus. Had pointy piincers. The other known crab resident (Mithrax, Leptodius sp. Family Xanthidae) has scoops on his pincers & I've always only seen him/her scraping the live rock, never witnessed him damaging coral. He will take food scraps of any kind as well though. When my BTA was new & sickly, the crab would try to steal chunks of silverside I was trying to feed the nem.

As far as ID for yours, the first one looks like it may be an Emerald, so relatively useful & harmless in most tanks. Check to see if his pincers have scoops as opposed to being pointed. The scoops are better suited to scraping algae & coralline off the rockwork, so that's what they tend to do most of the time. Pointed pincers are better at tearing stuff up, like your small fish or coral. I've never seen one like in your second picture, so no clue on that one.

[Kgrizzle]

Do emerald crabs tend to just stay in one spot inside of the live rock or r they more active at night or day?... Cause both these crabs have never been seen walking around the rock day or night.

Also none of them seem to look green

[mike31154]

Mine is not green either & think it's still considered an emerald crab. Not out much under the lights, except when feeding time. They can sense/smell when food hits the water, especially raw fleshy food like silversides or chunks of shrimp. Like I mentioned in my earlier post, an emerald would try to steal food from my BTA. Even my cleaner shrimp would grab stuff from out of it's tentacles. Now that the BTA is sticky & healthy, neither shrimp nor crab goes near it even when feeding silversides.

When I had two, each one seemed to hang out in opposite rock piles, territorial just like the fishes. They must have fought occasionally since both emeralds were missing appendages at various times. I'd definitely say more active at night. Get out your red light & you'll more than likely see it roaming around in the dark. Also depends on what other livestock you have in there & how long your system has been running. I see the crab out more often under the lights now that the tank's been up for years. Certain fishes don't take kindly to crabs & will take runs at them, depending on size & species. Survival instinct is strong.

[Kgrizzle]

Thanks guys I appreciate all the tips and starting to research ... The suspected emerald crab has pointy pinchers