Invert Spotlight: Emerald Mithrax Crab (Mithrax sculptus)

revhtree · Jul 4, 2012

COMMON NAME: Emerald Crab
SCIENTIFIC NAME: Mithrax sculptus
SIZE AVAILABLE: 1/2 inch
MINIMUM TANK SIZE: 1 per 25 gallons
FOOD/DIET: Omnivore
CARE LEVEL: Moderately easy
REEF SAFE: Considered safe, may be aggressive

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The Saltwater Emerald Crab is a great addition to any aquarium and is reef safe. They eat bubble algea and are very easy to take care of. Ample food needs to be present for them though as they will clean all the bubble algea out of the aquarium. Supplementing seaweed or chopped meaty food will suffice for them. They are also scavengers and will clean out most organic debris from the aquarium. Info Reefs2Go

revhtree · Jul 4, 2012

How many of you like to keep these types of crabs? Some people like them and others do not.

wysiwyg · Jul 4, 2012

i have 2 of them in my tank great scavengers

revhtree · Jul 4, 2012

They have always worked well for me at eating bubble algae. Others say they are hit and miss.

revsgirl · Jul 4, 2012

Cute lil' guys!

droblack · Jul 4, 2012

Ok when they are small, but can be problematic as adults. Mine would go after fish, and ate my porcelain crabs. Or maybe that was the Sally Lightfoot that ate the porcelains.

Bentonb · Jul 4, 2012

I've got one, and it seems to eat any algae that pops up. But I don't think I'll put one in my new tank they seem like they could do some damage if they wanted.

Blake11rebel · Jul 4, 2012

I have 2 small ones. I like the look of them compared to hermits. They do ok at cleaning up but I wouldnt count on them to much

icefish · Jul 4, 2012

I've tried them. They don't eat my bubble algae. Not a fan of them. I use a piece of tubing with a needle attached to it and suck the bubble algae out.

Steelerfan747 · Jul 4, 2012

droblack said:
Ok when they are small, but can be problematic as adults. Mine would go after fish, and ate my porcelain crabs. Or maybe that was the Sally Lightfoot that ate the porcelains.

That is what I have heard and there for not willing to attempt

k2parkstar · Jul 4, 2012

I'm not a fan of most crabs in general. Snails mostly for me. I've "heard" they can do some damage if they want, and i'm not willing to risk it either.

PolandSpring · Jul 4, 2012

I love em and hate em. They go after some corals some times but i had a major bubble algae outbreak in my 90gllon. I bought 5 of these and in 1 month every piece was gone.

steamer51 · Jul 7, 2012

Never had bubble algae thank goodness but I like my emeralds. Several times I have put a couple in and never seen them again but the last ones I got seem to be out in sight more, close to the rocks but viewable. I like their looks and have not had any issues with them eating corals. I hope they are not eating my snails (never caught them in the act) since I don't keep hermits for that reason. They are known to spawn in our aquariums and I appreciate the free coral food provided by their gametes if they are breeding.

BarbH · Jul 7, 2012

Has anyone had them do any damage in their tank? If so what did they do?

divewsharks · Jul 7, 2012

Females seem to a lot better, as far as not eating corals and such... They stay smaller and have much smaller claws.

ritter6788 · Jul 7, 2012

I've had some before but I rarely saw them and I don't have algae issues so I don't bother to get anymore. I'm not a fan of any crabs.

Pappy · Jul 7, 2012

They bulldoze everything for sure. They are great at eating algae and zoas though

they ate half my bam bam colony!

Mike D "like the beastie boys" Sent from my iPhone using Tapatalk

brian_reefragr · Jul 7, 2012

I've had about 50 of these guys throughout my reefing "career" and have had lots of different experiences. For me they typically have done well when they were introduced as nickel sized critters and there was plenty of algae for them to graze on. I have had some that continue to just graze on algae as they got full sized and others that started picking at z & p, as well as having seen some kill other tank inhabitants. I think some of my issues with them changing diets was that I ran out of algae and in my experience usually when they start scavenging they rarely have gone back to eating algae. All that being said I still really like em and will continue to have little ones in my cleanup crews.