How Bad Are Gorilla Crabs - Should I Get Them Out?

[Tobman]

I just received part one of the package and put it in my tank. There are at least two gorilla crabs in there. One of them I almost got out, but then he escaped.

The other I can see hanging out in a hole in one of the top rocks, and I bet I could get him if I pulled the rock out. Only problem is that there is a large sponge on that rock that I do not want to expose to air. Maybe I could pull the rock out and immediately stick it in a bucket of tank water and then fish him out in the bucket.

How bad are these guys? Should I really be that concerned that I should take them out if I can, of can I just let them be part of the environment and let them do what they will?

There is also at least one shrimp in there, as I can hear him clicking, but I haven't seen him yet.

 

[ckoral]

take a container like a canning jar, fill it with reef rubble to create a maze. At the bottom of the container put some flake food in there. You will have the crab trapped.

not sure how much damage they cause. I heard lots of rumors and that was enough to make me remove mine.

 

[Tobman]

Good idea. Does that work better than the plastic bottle trap that TBS posted on their website? Do you stand the bottle up or lay it on its side?

What's the purpose of the maze? I don't really have appropriate reef rubble yet. Could I use something else?

You make it sound easy, while it seems that others have tried and tried and failed to get their crabs out.

 

[ckoral]

the one I trapped was really fast. I get in there to get it out and he beat me. Lets just say in the end, I showed him who was boss. If you can get in and get it out quicker than it can move, you are don't need the rubble.

 

[Fountainhead]

I never had much luck with the bottle trick. Or any other "trap" for that matter. If you've just added part 1, then you've got time. Watch the tank on occasion and just wait for one of them to show up on a rock that you don't mind pulling out. A little ro/di water in his hole will flush him out. Or if you spot his hole and you don't want to pull the rock (because of the sponge for example) you can always leave the rock in the tank and ram a wooden skewer into his lair and possibly chop him up. Some holes are too deep of course, but it's worth a shot.

But do try to get them out before the tank gets too stocked. It's a much bigger pain to chase crabs when the tank is filled with corals.

 

[DocApoc]

I tried the ro/di water trick, and it totally failed to work for me. I even tried squirting soda water into the hole, and the crabs just wouldn't come out. (aslo didn't work on a mantis shrimp).

In fact, I think I did way too much damage to my tank trying to get rid of the pests during the cycle.

My advice is to not do anything about crabs during your tank cycle. If you try to trap them, your bait is adding nitrogen that you don't need, making your cycle harder. If you spear one in it's hole, it dies and rots in there, again adding nitrogen.

If you do a dip, you are going to be killing off some stuff on the rock, and again adding load to the tank. (I ended up with a white slime all over the one rock i removed and put in fresh water.)

My advice is to use tongs and a piece of shelfish on a stick to try to catch mantis shrimps, and leave crabs alone until after your cycle.

The only reason to try to catch the mantis shrimp early is because they apear to eat barnicles, and I didn't want to loose all my barnicles. But your choice there as well.

 

[tspfish]

As crude as it sounds the only luck I have had with getting rid of gorilla crabs is with a very sharp long wooden stick. They will eat soft corals when they get big and bold enough. I have got seven or eight of them this way, you just have to be patient and stab them at just the right time. Yes they are very fast!!!

Tom

 

[Tobman]

I have been having NH4 problems (off the chart) as the rock is just put in and there was something dying on it. At TBS' advice, I pulled all the rock out to clean off the dead material.

In the process, I managed to take out one large and one small gorilla crab, a stone crab, and a mantis shrimp. Another gorilla crab alluded my capture efforts by hunkering into a hole. So I'll have to try and spear him - right now he isn't coming out at all. I suspect once the tank settles, he'll start venturing.

 

[prestage3ek]

im surprised nobody has talked about using a chopstick or something to kill gorilla crabs and such, thats what I plan on doing once I get my stuff, no mercy is what im thinkin

 

[Tobman]

Just be a careful. The crabs are very fast, and you do not want to kill them if you can't then get them out, as they will then rot in your tank and cause huge NH4 problems. Try to get them out before you even put the rock into your tank, but if you can't because they are hiding in a hole, then leave them be and wait until they come out of their lairs once the rock is in the tank.

 

[Jocko]

Man I could never smash a poor crab like that.

I don't know about YOUR tank, but if I had a dead gorilla, the other critters in the tank would make a meal of him long before he'd "rot" in the tank.

 

[Tobman]

a chopstick eh? hope you've got the speed of Bruce Lee, cause them gorilla crabs are very fast. and so far mine have not come out of their lairs when anyone is around, they get even a wiff of me and they back deep under the biggest rocks in the sand.

 

[650-IS350]

just wait a hour or so after the light go out and hunt for crabs... they tend to come out after the lights come out...

once you find one with the flashlight you only have a few seconds while they are disoriented from the flashlight. I have a 2 foot mental rod that I use to stab them to death... I leave em' in their dying... The nassarius and stars go after em' the second I crack them open and left dying.... feels good seeing them get munch on instead of the other way...

 

[Ruu]

I'm on my third set of TBS rock now, and I just had the best crab catching experience in years. I picked up a new piece of rock to clean the detritus off it, and a large gorilla crab just literally ran into my gloved hand. I just closed my fist and lifted him out of the tank, and he now occupies my "bad" tank.

I am the crab wheesperer.

Dave

 

[wickedfood]

anyone ever get a mantis out without having to take rocks out to gett em? i have a nano, and it seems whenever i mess/remove rocks, even for seconds, i get enough die off to cause a little cycle. in the end, if i have to do this i guess i will b/c i want a couple fish, but man, what a royal pain.

anyone get a lot of nudibranches (sic?) with their rock? I've seen them stuck to the sides of my tank or on the rock eating stuff. I have no corals yet, but i understand the some nudis eat corals?? anyone have any advice here??

 

[Tobman]

do any of you with crabs still in your tank limit the types of corals you have, or will, add to your tank, due to what the crabs will do to them, like eat them? are your TBS tanks leaning towards FOWLR due to the limitations?

 

[hunter99991]

gorilla crabs

gorilla crabs

So what exactly do gorilla crabs do that is bad for an aquarium? I think I have one and I am trying to decide how much harm it is. It builds some pretty cool "forts" out of the sand that sort of makes me want to keep it.

Brent

 

[CMcNeil]

they can do damage to soft corals and should be removed.here is what i caught mine gorrila doing.i pulled the rock out and he never moved,was real easy to get rid of.

 

[650-IS350]

The bigger they get, the bigger damage they could do... Take time at night a few hours after the lights go out... use a flashlight w/ a red film covering it... and have a metal or hard plastic stick to stab/crush em'

 

[Tobman]

<a href=showthread.php?s=&postid=8514969#post8514969 target=_blank>Originally posted</a> by delsol650
The bigger they get, the bigger damage they could do... Take time at night a few hours after the lights go out... use a flashlight w/ a red film covering it... and have a metal or hard plastic stick to stab/crush em'

I'll try; I've got a red light now and a long hot dog skewer.

My biggest concern now is the mantis that is in there, whom I have never seen moving about, he is evidently extremely shy. His clicking sound always seems to be on the other side of the rocks, no matter which side you're on, which probably means he is underneath. Maybe late at night I can get him, with extreme patience. Last night I did go look at 12 or so with a red light and think I may have seen him peak out of a cave under the biggest rock, but then darted back in. Have been trying a mantis trap, with raw shrimp - have gotten some small crabs but no mantis.

I think I may have gotten all of the larger gorilla crabs. I've seen a couple of smaller ones only. Last weekend I got 6 gorillas by flipping over the top rocks when they were cruising. When they are underneath a rock, which tends to be most of the time, they cannot see you reach in and grab a rock. When I have pulled them on a rock out of the water, they seem to freeze, or in the case of the smaller ones, drop off the rock. The bigs ones frozen can easily be flicked off.