advise for catching night crab

Not sure if this is right section for this question but does anybody have advise or tricks for catching a rogue crab that has been appeared only in the dark of night. I have only seen him once or twice in the last 2 months and the last time I saw him he was on my Zoas which are slowly just disappearing. Not sure if he is the reason but needs to go. He was about 1 inch wide, orangish and scattered quickly with any light. Any traps, tricks, etc would be appreciated.

 

You think it can fit through top of a plastic water bottle?

If yes then cut the water bottle maybe quarter way down(from top) then take some food(or if zoa rock small enough) and put it in the bottom portion then take top part and insert it into bottom portion almost like you would use top for a funnel. Should trap the crab just like a crab cage would. If you use the zoa as bait you may find out something else is eating it and capture the culprit.

A crude technique but have seen it work for people

 

Some lfs rent traps for this very reason. My lfs has a $20 deposit on it, upon the return of the trap, they will give me my money back.

 

thank you both, the crab should fit through top of bottle so I will give it a try. In the meantime, I will contact local lfs for availability of the more professional trap but I like projects. It is frustrating seeing beautiful Zoas just vanishing.

 

Are you sure it's a crab? Did you see the crab actually eating the zoanthids?

 

No not sure at all, I have just seen it on zoas at night. This zoa rock has such a history. Started out as a gorgous large packed muticolor Zoa rock. after a couple weeks witness zoa polyps just floating in tank (some actually transplanted in other areas. Then noticed white spots so assumed Zoa pox. I then treated with Furan 2 with the well documented process for 2 rounds. Spots disappeared but still noticed some disappearing BTW very interesting point here when I was treating I notice the rock was encrusted with turkey wing bivalves after treatment I noticed that about half the zoas are/ were growing on live bivalves. I know this because after treatment i guess I killed some of them and they opened up so you clearly see the zoas on the two shells and the mouth gapped. I never knew that they were growing on these bivalve ( felt bad i killed some of them but some still alive). but getting back to your question so after dipping for parasites and pox (two different type of dips performed) and still some just disapperaring I am running out of culprits, absent moving higher in my system since some polyps are reaching. Yet some are very tight to rock (sorry bivalve lol). Who said zoas are easy!

 

Some are rather tricky.

You might consider a worm or Asterina starfish if you have seen any. Sometimes if you pick up the piece at night you might see a starfish under the piece.

Crabs can be really tricky to catch so I thought I might give you some alternative zoanthid eaters rather than waste your time trying to catch an elusive crab.

Sounds like you have a good handle on it.

 

tall glass next to the rock with some pieces of scallop in the bottom.

 

ahh, I get the concept, lean the glass against rock creating a slope, then too slick for him to crawl up. i like it. It will also allow the snails to get out. Definitely will need to wait till lights-out to put in because bait will not last a minute with my fish.

 

no slope, but thats the idea