What kind of crab is this?

[JGT]

How about using 50/50 hydrogen peroxide/water and inject bit inside the hole?

Worth a shot.

 

[JGT]

Worth a shot.

Or even a thick slurry of kalk injected in might work.

 

[SHNICI]

I have melanarus wrasse in the tank. You think he will take care of the crab when it comes out? @evolved

How about using 50/50 hydrogen peroxide/water and inject bit inside the hole?

Worth a shot.

Or even a thick slurry of kalk injected in might work.

The wrasse isn't going to touch it like I know, and it will hide it self faster than the fish go on it.
The rest peroxide and kalk will damage the coral more from inside. They are strong chemicals in that case, I think the iodine is the closes solution which may take it out w/o hurting the coral. in that hole you have many internal small and microchannels which the coral tissue use, with that strong chemicals you aren't going to kill only the crab, but also part of the coral for sure.
50/50 H2O2 (peroxide) from how many % solution ??? You can find 3%, 6%, 12% - 30+% almost any of them will damage the coral from inside, from the lowest 50/50 you aren't going to hurt the crab. With other words: with this 2 you will hurt the coral longer before you hurt/damage the crab.
You have to make it to go out, you can't kill it and leave it to stay inside, as it will rot and damage the coral again.

I hope that's enough to get understand it properly, just I can't find another way for your case.

 

[canadianeh]

The wrasse isn't going to touch it like I know, and it will hide it self faster than the fish go on it.
The rest peroxide and kalk will damage the coral more from inside. They are strong chemicals in that case, I think the iodine is the closes solution which may take it out w/o hurting the coral. in that hole you have many internal small and microchannels which the coral tissue use, with that strong chemicals you aren't going to kill only the crab, but also part of the coral for sure.
50/50 H2O2 (peroxide) from how many % solution ??? You can find 3%, 6%, 12% - 30+% almost any of them will damage the coral from inside, from the lowest 50/50 you aren't going to hurt the crab. With other words: with this 2 you will hurt the coral longer before you hurt/damage the crab.
You have to make it to go out, you can't kill it and leave it to stay inside, as it will rot and damage the coral again.

I hope that's enough to get understand it properly, just I can't find another way for your case.

It looks like I can try iodine then. Otherwise, I am bit in a pickle.

 

[SHNICI]

Be gentle and try to avoid too much stress on the coral. Have on mind you are "dealing" with it internal part. Don't keep it for longer with the iodine in (like I member 5-8min max will be enough to make the crab to come out. if no, it will kill it making it to shrink, and then you can take it out easy with tweezers with grip also and eyelashes tweezers probably can work for you (if isn't much bendet at the tip) to fit in the hole w/o damaging the skeleton, if don't use them, get another Please.