unable to keep zoas on rock

[CoralOfDuty]

I recently purchased a 75 gallon from someone on Craigslist and upgraded from a nano cube. The tank was already fully established and looked like it was cared for. Livestock*
Blue hippo
Pb tang
Sea urchin
Purple psuedo
Pink spotted goby
Maroon clown

So here's the deal. Everytime i put zoas in the tank they go missing overnight within 1 or 2 days. If i keep the zoas on a frag rack 1/2 inch from the top of the tank nothing can get to them and they stay safe. They have been untouched since i put the rack there a month aago.i started with giving away the urchin. Then the hippo. Then traded the powder brown. I even bought a harlequin to ensure the few asterina stars werent the culprit. I do not see anything that resembles nudis and would think they could get to the rack.*
There are 3 fish left of the originals and don't think there is any way it's them.*
There are 100s of colonista snails. Many brittle stars. Fire shrimp. Idk what to do. I'm ready to hang it up. This is terrible. And no the zoas aren't melting. Please help. My next step is taking out all the rock n letting it die. Then putting it back in.

 

[quagmire]

Sounds like you may have a xanthid crab. They are masters of hide and seek. They squeeze into small holes and crevasses of rocks and become invisible. You can look right at one and not see it until it moves. I don't think one would be able to reach your frag rack if it were high up on the glass without some sort of structure for it to climb on. To find it you could place a sacrificial zoa frag in a location that is easy for it to reach. If it is in your tank it will most likely seek out the zoas some time during the night. You would have to stare at the zoas all night or set up a video camera to catch it in the act. If you're going to take the time to bait it you might as well set a trap to catch it while you are at it.

 

[CoralOfDuty]

Thanks so much for that quagmire! I did a quick google search on xanthid crabs and have a great idea. Someone said to put a drinking glass into the tank with food/zoa at the bottom of the glass. when the crab goes in there, it wont be able to climb back up the glass to get out. I'm going to either try that or me and wifey will be back-to-back taking turns keeping watch. I highly doubt she will be on board with that plan though. Ill post an update once i know. really appreciate the help.
now i wonder if i can put flakes at the bottom of the glass though instead of killing another nice zoa.

 

[quagmire]

I'd use a zoa otherwise you will lure other creatures or fish into the trap. Make sure you give the crab some sort of ladder/rock to climb up the outside of the glass.

 

[CoralOfDuty]

Im going to place a baby food jar next to the set of rocks with the bait zoa inside. just touching the rockwork so the crab can climb in and not climb back out. once caught, i plan on making it get a job to replace my beloved zoos.

 

[quagmire]

Good luck. Where are you located?

 

[ajespo85]

I think you might have a astrea star with a taste for zoas. Could be, if no zoas were in the tank before, and now you added some, they could come out of the "wood work" and go straight to them. Some people have real problems with those stars. I have tons of zoas, and several visible asteas, but so far, I'm good. No problems yet.

 

[CoralOfDuty]

Thank you. Im in Patchogue. And if this works, i owe you a beer.

 

[CoralOfDuty]

@ ajespo. i thought that as well but the zoas are now on a frag rack way up high and nothing has bothered them up there. colonista snails and a turbo made their way up to the frag rack, so i would think that the stars can get up there too. its only when i put the zoos on the rockwork that they get decimated over night. crabs cant climb the glass so it does make sense.

 

[rtecanoe]

I'm in Oakdale and have some green zoas that I need to thin out if you want some to use as bait and not worry about sacrificing. The glass trick worked for me in the past when I needed to catch an emerald crab that grew a taste for sps. I buried it in the sand. Kept catching all the scarlet hermits though so it took a while.

 

[ajespo85]

My crabs have scaled my back wall and climbed onto my rack, not sure how, my rack isn't touching anything but glass haha. But.. I haven't seen stars on my rack since I put it up, 2 months now. I just know stars can and do eat zoas. Crabs will too, but crabs are scavengers, so if the coral is sick or dying, they will eat it.

 

[CoralOfDuty]

@rtecanoe that would be great! I would be happy to swap you the zoa that i was going to use instead of feeding it to the beast.

 

[CoralOfDuty]

Rip.

Rip.

They were really healthy a few days ago.

 

[ajespo85]

Do you have a peppermint shrimp? Also could be a culprit. It's hard to say without watching it closely at night

 

[CoralOfDuty]

yes. i have one in there. but he was with me in my old tank and was a model citizen. hes been interrogated and has no information.

 

[DgenR8]

I would use something deeper than a baby food jar. Crab may be able to get out of something so shallow.

 

[CoralOfDuty]

I actually have a mason jar that im going to use instead. Oh man i hope i get crabs tonight. ummm..... :/

 

[cullyisgully]

Use a Snapple bottler and put it right next to the rocks and see if that work

 

[CoralOfDuty]

Night 1 Update:
Frag is still alive in the mason jar. No luck yet. Maybe the crab did some recon last night. Planning the attack for tonight.

 

[150Ron]

When I set a crab trap its been with a mason jar or drinking glass. I do get quicker results if I put a rock over the top as well as the side ladder. They hang drop from the rock and fall into the glass. Works great