Emerald Crabs are NOT Reef safe!

[Diznaster]

Is there a chance they go after corals/fish/inverts when the algae supply is slim?

100% chance, have a small mason jar with their coral of choice handy to try and trap them if it happens to you. You can also use a T6 torx screwdriver to sneak up on them. When they are munching coral they seem to be in a state of euphoria and oblivious to impending doom.

 

[theKoolAidMan]

Just added a small one yesterday...so we will see. Got plenty of algae for it to much on.

Is there a chance they go after corals/fish/inverts when the algae supply is slim?

Possibly. I think general consensus is that keeping them well fed will reduce the chance of them going after other things, however I think much like Pygmy Angelfish in reef tanks, a lot if down to the individual specimen.

 

[Kimberely]

Agreed. I had a baby bta go missing one night. When I tore my scape apart looking for it I found my emerald crab had drug it into his little crevice and had already eaten over half of it. The crazy thing was that I fed the crab mysis or brine shrimp every night but it didn't keep it from deciding my nem was delicious.

 

[YumaMan]

Hey reefers, you're scaring me. These stories are horrifying. This thread is just in time for Halloween! Aaaaaah!

 

[NinnJinn]

Just added a small one yesterday...so we will see. Got plenty of algae for it to much on.

Is there a chance they go after corals/fish/inverts when the algae supply is slim?

YES!!!

I bought three Emerald crabs along with some trochus and nassarius snails and a chocolate chip starfish for my 125 about 7 months ago did really well. About 2 months ago one of the three Emerald crabs got huge and started wiping out my tank.

Now all I have is the big fat emerald crab and 3 assorted Hermits. He even got a hold of my chocolate chip starfish and pretty much ate it literally.

I have fish in quarantine currently and plan on catching the emerald crab and putting him in the sump before I put my fish in the tank.

 

[Kimberely]

Hey reefers, you're scaring me. These stories are horrifying. This thread is just in time for Halloween! Aaaaaah!

You have good reason to be afraid lol

 

[Xero]

was it male or female? I only keep female emeralds for this reason.

 

[Xero]

dupe post, remove please

 

[cmcoker]

was it male or female? I only keep female emeralds for this reason.

When I have kept them, I did the same. Though the lfs gave me crazy looks when I ask them to hold them up to the glass before they are bagged so I can sex them...

 

[Kimberely]

When I have kept them, I did the same. Though the lfs gave me crazy looks when I ask them to hold them up to the glass before they are bagged so I can sex them...

How do you sex them?

 

[cmcoker]

This is from a page about blue crabs but this applies to emerald crabs, found the link on NR from a old discussion.

This is looking at there belly, the males have the Eiffel tower shape, females have the triangle.

 

[Kimberely]

This is from a page about blue crabs but this applies to emerald crabs, found the link on NR from a old discussion.

This is looking at there belly, the males have the Eiffel tower shape, females have the triangle.

Thank you!

 

[DanConnor]

I have a bunch of females- but noticed they don't really eat valonia for me. I put some males in- so far they are ok.

 

[Diznaster]

This is from a page about blue crabs but this applies to emerald crabs, found the link on NR from a old discussion.

This is looking at there belly, the males have the Eiffel tower shape, females have the triangle.

Cool, wish I would have known this. I could have at least added a data point to the theory before the carcass went in the garbage.

 

[rkpetersen]

I've had them at various times. I've never seen them eating a coral, but I have seen one repeatedly scraping the surface of a goniopora, which stayed closed up for days, until I caught and banished that crab to the sump. Currently, I suspect a largish one may be involved in the recent disappearance of some shrimps and a goby. I will probably be removing the remaining ones from two tanks, when the opportunity presents itself.

 

[mattzang]

so i was getting some bubble algae recently and decided i'd get an emerald. did my research like a good boy, found that i should get a female crab so it stays small and hopefully more reef safe. got her friday and today she's munching on my kenya tree

this hobby lol

 

[Diznaster]

so i was getting some bubble algae recently and decided i'd get an emerald. did my research like a good boy, found that i should get a female crab so it stays small and hopefully more reef safe. got her friday and today she's munching on my kenya tree

this hobby lol

Darn it... Mine had plenty of algae and other things to eat, but went for corals instead. Have you caught it yet?

 

[mattzang]

Darn it... Mine had plenty of algae and other things to eat, but went for corals instead. Have you caught it yet?

nah, just noticed this today.. kinda hoping she was just going after something on the tree? wishful thinking..

my tank is mostly clean, but if she was going to be a coral eater, how about the endless amount of ugly trash zoas i have on my live rock!!!!!!!!!!!!!!!!!!!!!!!! i'd pay to find a fish that just annihilates zoas like they're going out of business

 

[vetteguy53081]

Like I said in previous comments- I don't trust them things. Too many chances and they mess up Every time

 

[erdrick80]

I don't know.. I' must be one of the lucky ones. Cause even though my emerald crab is pretty big, he doesn't mess with any corals although I don't have alot. He does he's duty as a cuc. And I love seeing him in my tank just picking at all that crap in tank that is not wanted. He is not going anywhere any time soon.