What kind of crab is this?

canadianeh · Oct 31, 2020

I bought lobo coral and it has hole on the bottom of it with a tiny crab living inside it. What kind of crab is this? Any concern?

John Genmel · Oct 31, 2020

Looks like a porcelain crab.. those are nice

vetteguy53081 · Oct 31, 2020

Pics very fuzzy- Hard to tell

sfin52 · Oct 31, 2020

Gall crab

vetteguy53081 · Oct 31, 2020

sfin52 said:
Gall crab

That would have been my guess especially with the hiding tunnel

JGT · Oct 31, 2020

canadianeh said:
I bought lobo coral and it has hole on the bottom of it with a tiny crab living inside it. What kind of crab is this? Any concern?

Hard to tell. Better pic would help. Think front claws would be telling. If no real discernible claws, then possibly a gall crab. If 2 distinct claws, then porcelain.

canadianeh · Oct 31, 2020

that’s the best I can take. It is inside so hard to get pictures.

is gall crab nuisance?

JGT · Oct 31, 2020

canadianeh said:
that’s the best I can take. It is inside so hard to get pictures.

is gall crab nuisance?

No, it’s fine. Scavenger so not bad to have.

canadianeh · Oct 31, 2020

Thanks guys!

here is the Lobo

JGT · Oct 31, 2020

canadianeh said:
Thanks guys!

here is the Lobo

That’s a beaut! If it is a gall and was on top you may want to consider removing as they can sometimes irritate the coral and cause them to not open but under shouldn’t be a concern.

sfin52 · Oct 31, 2020

vetteguy53081 said:
That would have been my guess especially with the hiding tunnel

Great minds think alike. I learned from you ud a couple

SHNICI · Oct 31, 2020

sfin52 said:
Great minds think alike. I learned from you ud a couple

gall crab for sure from the description, but have on mind, they aren't just detritus feeders, they are parasites! That's very important to be known. they feed from the corals filaments, and will eradicate them, here you can find many users which are after problems because of them, the last one I member was Gall crab in Elegance coral, eating it from inside...
Please compare that with your one: gall crab . If isn't looking like it (the claws - pincet) , that's one of the cases I can show you Elegance (not the last one since few days ago).
If Isn;'t looking like it at all, then try to get another photo of it when it's almost outside

canadianeh · Oct 31, 2020

SHNICI said:
gall crab for sure from the description, but have on mind, they aren't just detritus feeders, they are parasites! That's very important to be known. they feed from the corals filaments, and will eradicate them, here you can find many users which are after problems because of them, the last one I member was Gall crab in Elegance coral, eating it from inside...
Please compare that with your one: gall crab . If isn't looking like it (the claws - pincet) , that's one of the cases I can show you Elegance (not the last one since few days ago).
If Isn;'t looking like it at all, then try to get another photo of it when it's almost outside

So it looks like I have to get it out then. It burrows deep and I can’t reach it. I dipped the coral in revive and flatworm exit, but it survived. Any tips?

do they need another crab to reproduce? I only saw one.

JGT · Oct 31, 2020

canadianeh said:
So it looks like I have to get it out then. It burrows deep and I can’t reach it. I dipped the coral in revive and flatworm exit, but it survived. Any tips?

do they need another crab to reproduce? I only saw one.

I think the jury is still out on whether these guys are pests or not. They can be but others also “guard” the corals and help protect it from predators. If you want to get rid of it, I’d take epoxy that’s used for mounting corals and plug the hole he’s in. You’ll basically starve him to death.

canadianeh · Oct 31, 2020

JGT said:
I think the jury is still out on whether these guys are pests or not. They can be but others also “guard” the corals and help protect it from predators. If you want to get rid of it, I’d take epoxy that’s used for mounting corals and plug the hole he’s in. You’ll basically starve him to death.

That’s what I am thinking to do. But, who made the whole in the first place? Was it the crab? If the crab did this, that means it able to do escape by continue digging in and out on the top which will destroy part of the coral.

JGT · Oct 31, 2020

canadianeh said:
That’s what I am thinking to do. But, who made the whole in the first place? Was it the crab? If the crab did this, that means it able to do escape by continue digging in and out on the top which will destroy part of the coral.

Yes, they create the hole or gall, thus the name. There is a chance they could burrow through to the other side so may not want to chance it. I would remove the coral and get yourself a dental pick, the type with curved hook on the end and use that to reach into the hole and remove the crab. Then seal it with epoxy.

SHNICI · Oct 31, 2020

canadianeh said:
So it looks like I have to get it out then. It burrows deep and I can’t reach it. I dipped the coral in revive and flatworm exit, but it survived. Any tips?

do they need another crab to reproduce? I only saw one.

not sure for the reproduction, not sure is it only one (sometimes they are couple in 1 hole). About taking it out, really don't know what can help, that LPS it's looking fine at the moment, but not sure when can bet stressed by the crab.
I'm not sure but probably you can try to inject in the crab hole some treatment, not sure how good will be the crab with the iodine based DIP solution. Seachem for example sell iodine DIP, this one can be used undiluted for spot treating, so probably isn't going to hurt the coral if you fill a bit the hole with syringe with needle. And that's only typ like adwise but can't confirm is it going to work or no.
I'll fill for example 1-2ml Iodine solution turning the coral the hole to be on top closer to the water surface, I'll keep it still (at least 1/2 inch under the water surface, to can the crab think it's fine under the water), and will fill the crab hole slowly with the solution. I hope the crab to be unable to keep the solution and will come out of the hole, then I'll grab it with with tweezers with grip on them or something like, but not with something where it can slip out, it's very hard usually the gall crab, can't break it easy.

SHNICI · Oct 31, 2020

I'm not going to seal it inside, it can be pis** and to damage the coral completely from inside digging in, to escape.
And even after taking the crab out I'm not going to seal the hole, isn't that big, and hopefully the coral will overgrow it closing it. And they aren't protecting the coral at all, they are getting scared and back deep in the hole always if there is something over/near the coral moving.