Worried About manits Shrimp & Gorilla Crabs

[Tobman]

My only hesitation about buying the TBS rock at this point is the Gorilla Crabs and Mantis Shrimp. It seems from the anecdotal info. you all have posted on RC about using this rock, most everyone is happy with the rock, but many struggle with the above critters. So I am skeptical.

What is the best way to get rid of them once the rock is in the tank? Does it work well to let the "bad" critters get into the tank, out of the rock, and then pull the rock after a couple of weeks to try and get at them? Or just fish around for them in the tank? Or set traps?

 

[poknsnok]

I bought a small amount from them. nice looking stuff but full of nasties. At least mine was. I wouldnt get from them again, its just not worth it. JMO

 

[bobt2]

gorilla crabs are over blown. i still see one or 2 after 18 months, still havn't seen where they cause damage

 

[Tobman]

It seems the opinions on the nasties are 50/50, ok/bad

 

[HowardW]

<<< What is the best way to get rid of them once the rock is in the tank? Does it work well to let the "bad" critters get into the tank, out of the rock, and then pull the rock after a couple of weeks to try and get at them? Or just fish around for them in the tank? Or set traps? >>>


In my opinion, your best bet is to try and remove any unwanted hitchhikers before the rock ever goes into your tank, although you may still spot an unwanted crab or mantis afterwards.

In my experience, traps are not always that effective and you're better off just removing the rock with the bad crab or mantis and flushing them out using a large 50 cc syringe and some cold soda water squirted forceably into their hideout. I have also had success catching crabs using the grabber tool from Sears but those crabs are pretty fast and it may take quite a few tries to nab one of them.

I think by far the warst of the 'bad' hitchikers are the stone crabs, followed by gorilla crabs (once they get big) and then the natis shrimps. Those stone crabs will eat nearly anything and everything and will also burrow caves under all the large rocks and cause them to shift or fall.

All in all, these 'bad' hitchikers are overblown and once you catch them, you will have the coolest live rock available anywhere!

 

[bobt2]

when i see the crabs in the open i just grab them with my hands. as an alt, i made a spear out of some music wire sharpened at one end. thats how i got my 1 mantis. i have 3 tbs tanks and i,ve left in a lot of what people said were bad, ie, limpets and some of the hitchhicking snails. my tanks are filled with corals and i still can't see a problem. and i know theres still some gorillas in each tank. get the tbs and enjoy!

 

[JMAONE]

...

 

[JMAONE]

I have had the typical sounds when the lights go off for about 5-6 years now. I have never seen the guy actually but I bet it´s a Mantis schrimp. Today I saw a Turbo snail with a large crack on the shell..

If it´s a Mantis how old do these guys actually get? I´m hoping the guy would die of old age you see...

 

[blewando1]

I just got my 50 lb package last Friday. Knocked one big gorilla crab out of his hole into a quarentine tank. No luck with the carbonated water method. Speared a second with sharpened wood dowel. Have seen at least two other med size gorillas. No luck yet with my trap. Hear popping sounds.... the hunt continues.

 

[bobt2]

with luck, the sound you hear is a pistol shrimp, i got 3 in my 75 package and they come out often at feeding time.

 

[WoodlandsTXReef]

I bought 40lbs of coral rock from TBS about 2 weeks ago. After hearing all the warnings about the hitchhikers, I took my time with each piece, squirting soda water into the holes and searching for the nasties before placing them in my tank. I only found 2 mantis shrimps (the worst of the nasties IMHO)...one came out with the soda water, and I presently have him in his own little gold fish bowl. The other refused to come out of his hole, so I speared him. A number of crabs came out, none larger than a centimeter. I'm not even certain which ones were gorilla crabs... they are so small! I'm fairly certain I got all of the mantis shrimp. Overall, I'm very pleased with my live rock. It's much better than what I've seen here in the Houston area at the LFS.

 

[rockdiver]

I just put it all in you want to have a REAL reef well they dont hurt anything maybe snails get eaten but thats ok with me
cuz they are VERY cool to watch.

 

[BigRedDog1934]

tbs rock is like the hobby itself ive found. its a bit more tedious to deal with the hitchhikers but in time it pays off. i have had the package for about two months now and the cup and tube coral are growing great. i have also found things that are unexplainable like a bioluminating worm that lit up like a glowstick on a few occasions. and after two months of hearing the inevitable clicking noise i finally saw my first pistol shrimp. he came out of a hole in front of the rock, saw me, fired off a warning shot and took off.

i had three mantis total, all of which the lfs was more than happy to get. in the end it is time consuming but welll worth the effort.

 

[Tobman]

What I mind most about the crabs is what they eat. I've got at least two still in the tank, one I haven't seen, but I can see his burrows. The other has a body the size of a quarter or slightly larger. The rock came with some orange sponge on it and already most of it has been eaten by the crabs.

What I worry about is getting nice corals and having the crabs eat the corals.

Plus the gorilla crabs kind of give me the creeps, hairy and all. I guess they are natural though.

BigRedDog1934 - how did you get your crabs out?

I've tried the plastic bottle trap to no avail, maybe with more enticing food it will work. I might pull out the rock and try to get them, which might work, as they are burrowed under the rocks in the sand, not in a hole in the rocks, so when I pull the rocks, they will either be still in the sand or clinging to the outside of the rock.

The other point is that, while I've seen one of the crabs sticking his nose out of his burrow, I have never seen any of them wandering about. Anytime I get close to his burrow, the one that sticks his head out very quickly scoots back out of site, unless I move very slowly. So I don't see how I would ever spear them or scoop them up with a net.

 

[BigRedDog1934]

tobman - i have tried the traps and the starfish love it because he just scoops out the bait and head back to his home.

the best way i have found with the gorilla crabs is to use a sqeuer (sp?). it take sa lot of patience and is very tedious. the one that i use is flat and metal and i have found some bizarre fishing method that seems to lure the crabs out of the holes.

(i should say first that about 90% of the crabs i have lanced have been snuck up on while they are feeding on the rocks. it is hunting by any definition.)

i noticed after getting about 25 crabs out that the remaining crafty ones would hole up half way in their burrow as i snuck up on them. then if i went very slowly, i could mimic the motion of some intruding creature around the rim of their hole with the end of the spear. this seems to craw them out for some defense of their burrow, if only symbolic on their part. many times lately the crabs have literally grabbed onto my spear before i even went for them. at that point it is a matter of precision and speed.

this technique has been refined over about two months and seem to have gotten rid of almost all the gorilla crabs. i still have some stone crabs to deal with and am of course worried about the possibility of the next generation.

let me know if that helps at all. patience is very key to this little crusade.

 

[ybenormal]

Stone crabs become more daring as they mature and will eventually run toward you when you near the tank. Mine (RIP) would actually chase my hand around the sump.

If anyone in my area has a stone crab and is willing to part with it, let me know!

 

[Tobman]

Last night, I caught another good sized gorilla crab. I saw him grazing around underneath one of the upper rocks. So I slowly reached in, grabbed the rock, pulled it out of the tank and flipped it over. There he was and so I just flicked him off.

25 crabs! Crap.

I've gotten 4 so far (3 gorillas and 1 stone) all from flipping rocks over (I only have part 1 so far). So far since last night I do not see evidence of any more, at least not big ones.

To be honest with you, it makes me wish I had not gotten this rock, as full of life as it may be. The crabs are a PITA.

Do you have corals in with your crabs and do they eat the corals?

Did you get many crabs with your second shipment of the package, just the same as the first shipment, or is there a difference?

 

[BigRedDog1934]

sorry tobam - i have been away from my computer for a couple of days.

the truth is that the gorilla crabs are a pain in the ***. i especially remember when i got my first and second shipments in from tbs that i was under some real stress after being away from the hobby for about eight years. the gorilla crabs added to that. now it has been about two months and i am still tracking the bastards to some degree.

to answer your question though. last night i was thinking about my next tank and weather or not i would but from tbs. i thought about the 75 or 90 i may start and multiplied the amount of crabs by the increase in size. after all of that, however, i would still go with the tbs rock.

the reason is because after two months of tracking the crabs i am winning the battle and, unlike iraq, the insurgency is almost gone. in its place i have rock that contains all sorts of life that will grow and thrive for years to come. new coral is coming out and new creatures are still appearing. i am confident that i made the right choice, especially when looking at the "premium" rock offered at a pretty good lfs.

my patience has certainly been tried at times with the amount of creatures running around but i just personally think that it is worth it. my wife and i can spend all sorts of time looking at the tank finding new things happening.

what i would do differently is maybe a small fresh water dip or a more thourough inspection to shock some of the crabs off before placing it into the tank. when i got these two shipments before i had worked myself up about the mantis so badly that i felt like my hand was going to be amputated while doing this and flew way too fast thorugh the first steps.

i would also do a far better job aquascaping - a more wide and spread out formation not only looks 100% better, it makes the crabs far far easier to find and get.

here's a couple of pics from the tank today. (by the way, the little purple crab who i have named "little dude" has yet to be identified. he is a regular comedy act shooting in and out of his holes and hs done nothing to harm anything in the tank. if anyone knows what kind of dude he is i would love to know. i did hear from one guy who had a similar crab for two years and had no bad time with the coral or anything else.)

 

[Tobman]

Thanks BRD.

Two more questions:

So tell me, are the crabs eating your corals or anything? They have already eaten all of the sponge that came with my rock.

And, do you think you have an inordinate amount of them in your tank. I can only account for less than 8-10 in my tank so far, although I only have part 1. 25+ seems like a lot.

 

[BigRedDog1934]

hey tobman - i cant really say if the amount of crabs i have (that never really sounds right saying) is normal or wht. i have only ordered from tbs one time.

as far as them eating things the gorilla crab was busted messing up the tube coral but at the moment no major damage is being done. i just wanted to have a cleaner tank for when i do start adding some nicer things. at the moment i have both xenia and a brain corl that are doing just fine.