Why can't I keep emeralds??

monkeysee1 · 07/03/2021, 07:36 PM

Hi again!
Has anyone else here had difficulty keeping those Green Mithrax Emerald Crabs??
Mine NEVER last more than a month!
I feed them Nori regularly, and here are my water parameters:
pH = 8.3
Alk = 10 dKH
NitRITES = none detected
Ammonia = none detected
NitrATES = 20 ppm (could THIS be the problem??) I dose with vinegar.
Phosphates = .10 ppm

Really weird because all my fish are doing great, as well as my snails, 2 urchins, 2 shrimp, and I have SEVERAL hermits. All of those are also ok.
Really unfortunate because I really like the emeralds but I'm reluctant to add any more until I find out the root cause of this problem. Or are they just too plain hard to keep for most aquarists??

Any insight from anyone would be appreciated.

Timfish · 07/04/2021, 06:46 AM

There's probably more than one reason. Two come to mind. First is stress from shipping and handling, especially if they are all from the same source. Second is predation, they are pretty safe most of the time but when they molt they are very vulnerable, it's possible one of your current livestock recognizes it and kills them when they molt.

cody6766 · 07/05/2021, 09:48 PM

Don't lose too much sleep over it. I've never been able to keep them in my tanks without issue. In fact, I don't keep any crabs in my tanks for the same reason. After a while, they seem to get bored with the normal "crab fare" and go after coral. They usually pick on LPS corals, but I've seen them bother a softie on an occasion or two. Chalice, favia, favites, and acans are the biggest risks in my experience. Maybe it doesn't happen in larger tanks, but I've seen it in 40g and less. I never added crabs to my 120, so I can't comment.

BTW, I've seen peppermint shrimp do the same thing. Coral aren't their normal diet, but they seem to adapt.

DoUEvenReefBro · 10/13/2021, 10:30 AM

I went through 3 emeralds before one stuck. Idk could be the stress from transport someone mentioned.

Also, I would go for weeks thinking that the last one was a gone but then it would come out randomly at night. If you haven’t seen yours in a couple of weeks it could be that it’s hiding.

Sent from my iPhone using Tapatalk

vsiege · 10/17/2021, 04:24 PM

Had one just die myself. Made it a few months. Eat like crazy though. While they are fascinating, I'm not certain I've had one for more than a few months. I had to relocate a smaller polyp zoa as one night he are all but 1. Finally have 4 heads 2 months later. Never seemed to touch anything else (that I'm aware of). Cool crabs

buy I haven't cracked the secret to keeping them myself. Hoping you have better luck with next one.

SantaMonica · 10/23/2021, 03:39 PM

Could always try to grow more bubble algae to feed them.

07/03/2021, 07:36 PM	#1
monkeysee1 Registered Member Join Date: Mar 2015 Location: MERRIMACK NH Posts: 423	Why can't I keep emeralds?? Hi again! Has anyone else here had difficulty keeping those Green Mithrax Emerald Crabs?? Mine NEVER last more than a month! I feed them Nori regularly, and here are my water parameters: pH = 8.3 Alk = 10 dKH NitRITES = none detected Ammonia = none detected NitrATES = 20 ppm (could THIS be the problem??) I dose with vinegar. Phosphates = .10 ppm Really weird because all my fish are doing great, as well as my snails, 2 urchins, 2 shrimp, and I have SEVERAL hermits. All of those are also ok. Really unfortunate because I really like the emeralds but I'm reluctant to add any more until I find out the root cause of this problem. Or are they just too plain hard to keep for most aquarists?? Any insight from anyone would be appreciated. __________________ Your "fair share" is not in my wallet; it's in my fish tank!! Current tank info: 90 Gallon saltwater 10 fish with a few inverts; NO CORALS! Tried to go reef; didn't work out so hot; FOWLR's for me!

07/04/2021, 06:46 AM	#2
Timfish Registered Member Join Date: Jul 2010 Location: Austin, TX Posts: 1,985	There's probably more than one reason. Two come to mind. First is stress from shipping and handling, especially if they are all from the same source. Second is predation, they are pretty safe most of the time but when they molt they are very vulnerable, it's possible one of your current livestock recognizes it and kills them when they molt. __________________ "Our crystal clear aquaria come nowhere close to the nutrient loads that swirl around natural reefs" Charles Delbeek

07/05/2021, 09:48 PM	#3
cody6766 Super Best Friends! Join Date: Jan 2008 Location: OKC, OK Posts: 3,772	Don't lose too much sleep over it. I've never been able to keep them in my tanks without issue. In fact, I don't keep any crabs in my tanks for the same reason. After a while, they seem to get bored with the normal "crab fare" and go after coral. They usually pick on LPS corals, but I've seen them bother a softie on an occasion or two. Chalice, favia, favites, and acans are the biggest risks in my experience. Maybe it doesn't happen in larger tanks, but I've seen it in 40g and less. I never added crabs to my 120, so I can't comment. BTW, I've seen peppermint shrimp do the same thing. Coral aren't their normal diet, but they seem to adapt. __________________ "The moral is the chosen, not the forced; the understood, not the obeyed. The moral is the rational, and reason accepts no commandments." - John Galt Current Tank Info: Cadlights 60G Arisan II mixed reef with 2x MP40s and 24" ATI

10/17/2021, 04:24 PM	#5
vsiege Registered Member Join Date: Sep 2011 Posts: 181	Had one just die myself. Made it a few months. Eat like crazy though. While they are fascinating, I'm not certain I've had one for more than a few months. I had to relocate a smaller polyp zoa as one night he are all but 1. Finally have 4 heads 2 months later. Never seemed to touch anything else (that I'm aware of). Cool crabs buy I haven't cracked the secret to keeping them myself. Hoping you have better luck with next one. __________________ Seahorse setup: 37 gallon; Reef Octopus BH-1000 HOB, Marineland Penguin 200, LEDs Searching for: JBJ chiller and a canister filter

10/23/2021, 03:39 PM	#6
SantaMonica Registered Member Join Date: Feb 2007 Location: Santa Monica, California, USA Posts: 2,511	Could always try to grow more bubble algae to feed them. __________________ Inventor of the easy-to-DIY upflow scrubber, and also the waterfall scrubber that everyone loves to build: http://www.reefcentral.com/forums/showthread.php?t=1424843

10/13/2021, 10:30 AM	#4
DoUEvenReefBro Registered Member Join Date: Jan 2019 Posts: 26	I went through 3 emeralds before one stuck. Idk could be the stress from transport someone mentioned. Also, I would go for weeks thinking that the last one was a gone but then it would come out randomly at night. If you haven’t seen yours in a couple of weeks it could be that it’s hiding. Sent from my iPhone using Tapatalk