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makolonj
06/26/2009, 09:40 PM
I have 3 emerald crabs in my 120g and about two weeks ago their exoskeleton's seem to have begun turning white!
This can't be a good sign...any thoughts? Magnesium perhaps...

Everything else (fish and coral) seem unaffected.

romsoccer12
06/26/2009, 10:41 PM
mine are doin the same. i thought they where about to molt but they just keepig getting more white spreading through their
body.

makolonj
06/26/2009, 11:28 PM
I know their eating b/c around their home there's about 10 snail shells, fish food, and about 1,000,000,000 bubble algae to choose from.

wschang812
06/27/2009, 02:23 AM
ive seen that happen. very weird. i was thing they arent getting enough green in their diet but i guess im wrong

FabRight
06/27/2009, 03:36 PM
I have one that is doing the same thing. I hope someone chimes in with a good reason. I thought mine turned white because I recently dosed Mg.

400M1963
06/27/2009, 05:09 PM
Make sure you have iodine/iodide supplement to help molting. They feed on algae and that helps color them green. If not enough present, supplement with seaweed, like Julian Spung's. Nice when they're small but like most things in reef can range far afield and start snacking on corals, snails or other crabs like hermits when they get burly. At that point esp. if not pulling their weight with bubble/hair algae chores, many reefers find them another home.

romsoccer12
06/27/2009, 05:24 PM
i feed my emeralds with hikari every once in a while. i heard that your not supposed to put in iodine

makolonj
06/27/2009, 05:54 PM
any other thoughts?

400M1963
06/27/2009, 06:24 PM
http://74.125.93.132/search?q=cache:bxobiAuK2p4J:www.freshmarine.com/emerald-crab.html+mithrax+iodine&hl=en

Emerald Mythrax Crab Description
Taxonomy: Emerald Mythrax Crab belongs to the Kingdom Animalia, Phylum Arthropoda, Class Crustacea, Order Decapoda, Family Majidae, Genus Mithrax and Species sculptus.

Scientific names: The scientific name of Emerald Mythrax Crab is Mithrax sculptus.

Other common names: Emerald Mythrax Crab is also commonly known as Emerald Mithrax Crab, the Green Crab, the Emerald Crab and the Green Mithrax Crab.

Origin or natural range: Mithrax sculptus originates in the Tropical Western Atlantic region, Caribbean.

Size: Emerald Mythrax Crab grows up to around a size of three inches.

Color: Mithrax sculptus occurs in green color.

Compatibility: Emerald Mythrax Crab is semi-aggressive towards the other marine aquarium invertebrates.

Habit & Habitat:

Mithrax sculptus is found in abundance in small loose groups in its habitat.
Emerald Mythrax Crab is nocturnal in habit and therefore, hides during the day time while coming out to feed in the evening.
Morphology:
Emerald Mythrax Crab is quite hardy.
The body of Mithrax sculptus is flat, compact, shiny and is green in color.
The legs of Emerald Mythrax Crab are ten in number and are hairy.
The first pair of legs of Emerald Mythrax Crab is developed into large claws that are flat at tip to pull off algae.
The head of Mithrax sculptus is joined to thorax.
The thorax of Emerald Mythrax Crab is covered by a rough shell called carapace which measures around 2.50 to 4.00 inches in width.
Mithrax sculptus hides its soft and small abdomen and tail as well under the carapace.
As Emerald Mythrax Crab outgrows the existing shell, it sheds the shell off, a process called molting, and a new shell replaces the old shell.
Mithrax sculptus leaves its old shell at a visible site to dodge its predators while hiding away to allow the new shell to form completely and harden.
Emerald Mythrax Crab has two pairs of antennae and three body parts.
Growth enabling environment in your marine aquarium:
Temperature of water: Seventy-two to seventy-eight degrees Fahrenheit.
Specific gravity of water: 1.023 to 1.025.
pH of water: 8.10 to 8.40.
Habit & habitat: To host Emerald Mythrax Crab, you should have a large reef type marine aquarium with ample rocks, crevices, caves and the other dark and shady areas in it.
You can keep more than one Mithrax sculptus in your marine aquarium.
Emerald Mythrax Crab adjusts to your marine aquarium environment in around an hour.
Mithrax sculptus is so adaptable that despite being nocturnal in its natural habitat, it adopts flexible-timings to become active whenever it needs to.
Emerald Mythrax Crab grows well in a favorable marine aquarium environment.
Feeding & Nutrition: Mithrax sculptus is an Omnivore and a scavenger in feeding habit.
Emerald Mythrax Crab eats micro-algae including the unwanted bubble algae (valonia) and cyanobacteria, detritus, pellets, seaweed and the frozen meaty bits of seafood. Therefore, Emerald Mythrax Crab also helps keep the tank free of many undesirable micro-organisms.
If your marine aquarium does not have enough algae then supplement the tank with some herbivore food items and meaty bits.
When grazing its food in your marine aquarium, Mithrax sculptus holds on to the rocks therein.
Add Iodine to the water to smoothen up the crab’s molting process.
Breeding: It’s difficult to breed Emerald Mythrax Crab in a marine aquarium because the hatched larvae are too sensitive to adjust to a captive environment.
Care: Mithrax sculptus is easy to maintain owing to its non-poisonous nature.

Caution: When grown up in size, Emerald Mythrax Crab may attack small fish and corals in your marine aquarium to feed itself well. Therefore, avoid keeping corals and small fish and Mithrax sculptus in the same aquarium.

milkit
06/27/2009, 06:47 PM
after having my cleaner crew over a month, in the past 2 days ive found 2 emerald crabs dead and white, and i am missing 2 peppermint shrimp. One i saw dying, then another one grabbed the body and was picking at it before a snail wrapped around it and sucked it dry.

paramaters are normal with the exception of phosphates which are high. temp is slightly above normal too (about 81-82).

I dont have an iodine test or anything but i do water changes more than i probably should

jenglish
06/27/2009, 07:10 PM
I would not supplement anything you are not testing for. Dosing iodine will cause a crab to molt but that doesn't mean it is healthy and growing. Inverts will bind up excess iodine in their exoskeleton and then rid themselves of it by molting. Lots of waterchanges would only help to replenish iodine, not deplete it, assuming you are using a decent salt.