Setting traps for crabs
 

I'm pretty new to reef keeping and this site has been invaluable teaching me so much. Would like to thank everyone.

I set up my 10 gallon nano 2 months ago with a bunch of live rock. About a week ago I bought 9 more pounds of live rock from someone's personal tank and I have now noticed a black and white striped crab in the rock. I've only seen him maybe twice since hes always hiding. Now I know crabs are bad things to have in a reef so I'm wondering what would be the best way to trap him and get him out of the tank. I heard lots of people put food in a glass and hope to catch the crabs at night. Is there any other effective method any of you guys have used?

Thanks again.

I think they're innocent until proven guilty... there are SO many undocumented crab species, that you can't predict how it'll behave by looking at it.

but that's my opinion.

I actually found a crab hitchhiker that I quite like on my own rock. It's exactly like an emerald crab, yet black. it's behaved himself quite nicely for a month now.

a very loose way of determining whether it is good or bad is by examining the pinchers, if they are large and rugged and can rip through something more than likely they are bad, if the pinchers are small and hairy than possibly they are safe. but like i say it is a loose determination

The only crabs I EVER worry about are the ones living inthe acros (the hairy ones, not acro crabs). The ones that live in the rock, I try to spot feed. I was looking in someone's tank the other day and he had 2 large ugly scary looking crabs come out and start eating algae off the rocks. I'd like to be able to get more of those!!

So you guys think I should wait and see if he eats my zoos and let him stay until then? Wouldnt it be hard to know if hes attacking them since hes only out at night? I heard if I get a red flashlight they wont see the light and I can observe the tank at night, true or false?

The only crabs I like are filter feeding crabs. The rest gotta go :twised:

Videos of crabs we've caught in our old tanks....

Caught in our 37g - Red Eyed Crab
April 8, 2006
(320 x 240 pixels, 3.6 MB, :49 minutes)

Caught in our 37g - One Black Claw Crab
April 14, 2006
(320 x 240 pixels, 7.8 MB, 1:38 minutes)

Caught in our 67g - Mystery Crab
April 13, 2006
(320 x 240 pixels, 9.7 MB, 2:02 minutes)

Caught in our 120g - White-Backed Brown Crab
April 22, 2006
(320 x 240 pixels, 21.3 MB, 4:30 minutes)

Anyway, the best ways to catch crabs, IME, are....

1) Find out which rock they're in, remove the rock and use long poking sticks, thin screwdrivers or simliar implements to get them out of their hiding places.

2) Just before lights out, put a piece of bait in the bottom of a glass, prop the glass at a 45 degree angle against a rock near the crab's hideout is, and hopefully in the morning you've caught a crab.

I have crab catching 2 or 3 videos where we discovered a really strange worm in our 120g. Will post them if you like, but they are mainly geared toward the weird worm.

Sure post them that would be great

Bev is the master of crab catching. She's given me a few little critters for my sump. A 'black emerald crab' included.

That little guy actually crawled out of my sump about a month ago. My cat found him and was swatting him around the place until my wife saw this and saved the little guy!

Hey my crab just looked like this. Found a web page that labelled it as "Gorilla Crab" yet I don't think that this is a very recognized name.
I used method 1) to catch it. Well first I moved the rock out and waiting as someone told me that they would come out themselves after a while on their search for water. Waited for 30-40 minutes and got inpatient so then used 1).
He looked really cute and I brought him to my local store hoping I could trade him in for something. Well he was used as fish food. :neutral: Couldn't stay to watch it. I even had some nightmares I think as I felt responsible for this poor little guys death... :puppydog: I'm just a big sob when it comes to that.

Bev, great videos! I absolutely LOVE the first couple of seconds of this one with the pincher emerging from the coral.

So do you guys think a crab would survive in a small 2.5 g tank with a little LR and LS? It would probably just eat shrimp pellet hey? Reason I'm asking is that after hearing how angelfish's crab was turned into fish food at the LFS im thinking maybe I should just keep this guy in his own little tank.