Hitchhiker Crab?

joro · Feb 9, 2017

We just recently discovered his Crab which we didn't add intentionally but seems to be pretty strong (my wife noticed it because he grabbed a feed tube thing we were using on some corals lower in the tank). He's a red / tannish in color and definitely has hairy legs. We haven't seen him fully out but he seems to be maybe the size of a nickel or so. We've also noticed since we found him, our female Manadrin is not to be found - the male mandarin and others (Midas blenny, helfrichi firefish, 2 clowns) however, seem to be fine thus far.

Any ideas on what it is and how to remove it? I've tried using angled tongs a few times and we've also had the baited glass in there the past 2 nights but no luck.

Hyde2406 · Feb 9, 2017

Looks like it has black tips on his claws, gorilla crab? But I'm no expert

Hyde2406 · Feb 9, 2017

Best way to get him out is to pull the rock out and blast hot tap water on him till he runs away if you can't just use tweezers and pull him out

Lninwa · Feb 10, 2017

Or better than pulling the rock out is to fill a small glass bottle with tank water and put a cube of frozen mysis Put the top on bottle, after it's submerged on the bottom undue the cap. Make sure the bottle opening is upright. Take the top off. Next morning you should have your crab inside. He can't climb out once he's in

mallorieGgator · Feb 12, 2017

I used to just take a sharp fondue fork and poke through the back and pull the dead crab out on the fork. Unless you want to save it. Then that doesn't work obviously.

joro · Feb 12, 2017

I was actually able to capture him last night with the baited glass approach. Definitely a gorilla crab, now time to figure out what I do with him

ebushrow · Feb 12, 2017

Sump or flush....that's the question....

Hyde2406 · Feb 12, 2017

Rory · Feb 20, 2017

A trick I learned (and worked catching a Mantis hitchhiker) is to spot his hole in the rock... pull that piece out and use a turkey baster to spray in club soda! He will shoot out like a rocket and you won't harm anything else on the LR

Oldsalt · Dec 6, 2018

I have just been able to spot the crab that's just killed my gorgeous Blenny. The Blenny (lawnmower type) had to be easy pickings because he slept right under the rock that also housed this gorilla crab. When I pulled out my poor Blenny it had vertical lacerations. Before I was able to grab him with a long grabbing tool, I actually got to see the crab for the first time Hairy legs and happily dining on Benny's guts. Now I know for certain this gorilla crab is the culprit and that he needs to go quick smart before I lose any other fish. Luckily my 350 gallon tank is sparsely stocked with 7 green/blue Chromis, 7 small shoaling blue/orange damsels and 1 small yellow tail-blue Chromis who likes to shoal with the green blue Chromis. I finished the cycle 3 weeks ago. 15 small fish (was 16 before Benny was taken last night) isn't much considering the size of the display tank - the sump is 150 gallons but is holding 100 with its level smack in the middle of the lowest line and highest line. This gorilla crab had to come with the last batch of live rock I bought here in Perth Western Australia. There's 100 kg (220 lbs) of LR in the display and around 20 kg (50) lbs of it (smaller porous pieces) in the sump. It's going to be very difficult to pull up any rock (the piece that hairy legs calls home is huge and heavy) as they are locked in to each other very tightly - besides, the tank is 3 feet deep (30 inches up is the water's surface). It took 16 hours all tolled, my entire arm's length and a step ladder to aquascape this aquarium - I'm not a spring chicken at 63 years old. So I'm going to have to try the baited jar and crossed fingers tomorrow night. I'm slightly worried that I may also have either a mantis or pistol shrimp somewhere because I sporadically hear a clicking sound. I'm not sure if crabs can make these sounds. When I get the gorilla crab out, I'm praying that the clicking sounds go away as well, otherwise I'm going to need to devise another plan to tackle that issue. The clicking sound is not loud. 25 years ago I had a 6x2x2 tank with a mantis shrimp within and he was super loud compared to the noise I'm hearing now. I actually managed to get a photo of this gorilla today as he was dining on my recently added Blenny. I can't seem to find a way to attach a photo here. Any suggestions would be great - not just for attaching a photo, but also about how to best go about ridding my new tank of unwanted critters. Seeing as I recently gotten the itch for another marine tank after over 25 years without one, so much has changed for the better in our hobby. On an aside, I still have the very first protein skimmer I ever used back then. It's one that uses the wooden air 'stone' and it cost me a fortune - going by 25+ years old monetary calculations! I'm going to use it in a quranteen tank, lest it goes to waste.

cracker · Dec 6, 2018

Put it in the sump ! It would be good at keeping it cleaner.
If Your going to flush it,mind as well put the little devil to good use by turning it into food for the others
After all it "would" eat your fish !

Oldsalt · Dec 6, 2018

cracker said:
Put it in the sump ! It would be good at keeping it cleaner.
If Your going to flush it,mind as well put the little devil to good use by turning it into food for the others
After all it "would" eat your fish !

He's going in the sump for sure. Got a good look at him today. Hairy legs. He's very large. I don't know how I missed him before putting in the LR. there's a nice hole abide him. Probably he was right inside not letting go My poor Blenny was sliced in half.

cracker · Dec 6, 2018

It Munched you Blenny? Well in that case , deal with extreme prejudice !

Oldsalt · Dec 7, 2018

cracker said:
It Munched you Blenny? Well in that case , deal with extreme prejudice !

Got him early this morning using a jam jar baited with shrimp. I stuffed a half inch tube full of misis shrimp and hot glued that to the bottom so it wouldn't float up. That was my 2nd try after learning tubing likes to float up especially with air bubbles within the shrimp. Took me an hour all up plus planning and placing before hitting the hay. Here is the little killer. He's going into the sump where he will be treated just fine. Besides there's plenty of cleaning there to keep him busy.

cracker · Dec 7, 2018

Good Job !
Also, I laud your mercy !

Oldsalt · Dec 7, 2018

I'm no killer!

Katrina71 · Dec 7, 2018

I'm sorry about your Blenny

. It's cool that you didn't kill him and just gave him an appropriate home instead.

Oldsalt · Dec 8, 2018

I watched the crab in the jar and my dog wanted to know what I was doing so I showed him it. My dog started to lick the jar as I asked "what should I do with Mr crab?" I looked at the crab again and just couldn't bring myself to flush him down the toilet. The LFS said they didn't want him back either (he hitchhiked on a large LR I recently bought from them) so I decided to drop him in the first (refugium) section. He's quite happy there and can't escape because it has smaller bits of coral that aren't tall enough to climb up, plus the outflow goes up and over into the 2nd section where the algae scrubber is going to drain into - so he can't go under either because it's sealed. The best he can try for is to climb up vertical glass. We've just proven that won't happen! I doubt he will need much feeding as any detritus that's missed by the pre- filters stays at the bottom of his section. That will save me a lot of work.
As for the poor Blenny, my LFS said they'll give me another for free. They have over a dozen.