Is crab eating my corals

[Roboson]

So what you're looking at right there is the Black Mithrax crab. He's the darker more dangerous version of the Emerald and Ruby Crab. Mithrax crabs are voracious scavengers and algae eaters, the black type especially. While not evil inherently, they need a ton of food.

They're nocturnal, highly skittish, and grow much larger than the Emerald variety. If your guy is bigger than the one above, the poor thing is starving to death in your aquarium.

If you can get him out that would be great, but it may not be an option. He will not stray far from where he feels safe. I would honestly suggest trying to spot feed him meaty food and appease him instead of dismantling a tank to get him out.

When I started thinking about it, a mithrax crab (and a desperate one) is the only crab that made sense. Stone crabs wouldn't venture up onto acro for their tips (but may have attacked sand bed coral), and a shore crab wouldn't be hairy or skittish. That leaves the mithrax crab, which are much less dangerous than the other two prime suspects.

 

[Vincent100]

thanks roboson you have been a big help
so there is a chance that hes picking , its only the new growth on the acro thats been picked at and thats gonna be the only soft part of the coral
the other coral has not been touched since and looks the same .

do you think a glass leaning up on a rock with some shrimp in it would get him

 

[Roboson]

Honestly, not really. He's probably going to be suspicious of anything new near his hidey-hole. If you know where he is, drop a piece of shrimp by him. If he acquires a test for shrimp, he may fall for that trap. But right now he knows coral tastes good and is safe.

Maybe try the garlic trick and put it in late at night.

 

[Roboson]

Any updates?

 

[Vincent100]

Any updates?

Hi robo

Got a pic of him ... Well abit if him , Iv been feeding him prawn Goes crazy for it claws flying everywhere , he likes this hole aswell .
Cleaner shrimp tried nicking food off him but soon moved out of hes way ....good I hate that shrimp ..... Coral feeding time robber lol

 

[Roboson]

Once he gets a good taste for the bait and is used to getting fed by you, you should be able to put a trap out for him.

Here's what I would try:
Take some fishing line and tie it around the top of a glass jar.
Put some bait in the jar and place it horizontally next to his hole right before lights out or whenever you've been feeding him.
Wait for him to go into the jar and then pull on the line so the jar turns upright.
At that point you got him and you can remove him from the tank.

If it works post a few pics of him, he'd make an awesome sump pet since he'll eat whatever.

 

[Vincent100]

gonna do it , ill wait till hes gets use to me feeding him some more than ill set the trap , i caught a coral nipping fish that way as well pull the bottle all the way to the top ....this way iv only gotta get it to stand up

ill post pics once iv got

 

[Brew12]

Has the coral damage stopped since you started feeding him? (sorry, can't help but follow this thread!)

 

[Vincent100]

Has the coral damage stopped since you started feeding him? (sorry, can't help but follow this thread!)

hi brew , good to have you following the thread
iv not seen anymore ....hope it stays that way lol
i make sure i have a good look over the tank last thing at night and first thing in the morning .
All on me to get him out now and sump him

 

[najer]

My Black mithrax is about 40 mm across the shell, jet gloss black with white tips and joints, he gets a weekly part algae grazer and I have never seen any coral damage I would put down to a mithrax.

 

[Roboson]

They aren't evil, but they do have a big appetite. Once they're big enough to measure in inches is when you're gonna run into trouble. Honestly I think that they're wonderful sump pets because of that same reason. They'll eat up excess food that gets down there and help keep the aquarium clean.

 

[Vincent100]

Well that's the end of that one

 

[najer]

Is it dead or did it shed?

 

[Vincent100]

Dead as a door nail mate

 

[Babygecko1233]

Awww....why did it die ??

 

[Vincent100]

I'm not to sure , I was spot feeding it

 

[Babygecko1233]

Maybe he just out grew the tank? Or lived his whole life cycle? He reminds me of a whip scorpion

 

[Babygecko1233]

I had a stone crab as a hitch hiker once...didnt realise him before it was too late... He ate everything....and was HUGE he staid hidden very very very well....i captured him when i did an aqua scape trying to figure out what happened to all my critters (trigger fish, file fish, sea urchin).. Im not scared to get pinched so i grabbed him...nasty crab!! Pinched me down to the bone!!! Had a nasty gash for a long time!!! Evil little boogers!! Put him in the qt so i could release him the next time i went to the beach...well....that didnt work...he some how crawled up my filtration and out into my room...my step dad found him gaurding the sugar on the kitchen counter...next to his morning coffee. It was a strange occurance...and we still cant figure out why or how he got on the counter... He escaped many more times ( found him under dirty towels ect.) until finally we went to the beach..where i let him go...he was a happy crab and immediatly began eating and found himself a nice cubby whole in the inlet rocks.

 

[Vincent100]

Well I was 100% sure what i pulled out of the tank was a dead crab not a molt , I had a good look and was sure .....anyway today I saw another crab or the same crab lol, but bigger

I must of made a mistake , most of the time a molt falls to bits and you can see ...... See through bits
Pic are not that clear but u can see him
1st pic is the old one that was dead
Maybe not lol
The other pic are from today
Please fill free to call me names I'm a big boy and can take it haha

 

[Brew12]

Please fill free to call me names I'm a big boy and can take it haha

Ok Names, good luck catching that sucker!