Black??? mithrax (Emerald) crab

[KrautBurner]

sorry,

no pics of my actual crab (he dosn't like movement outside the tank )




I picked up 6 green mithrax crab's from SWF.com about 7-8 months ago.
gave a couple away when swapping (upgrading) tanks.

I've still got 2 green ones,
but recently, I've been seeing a Black one crawling around the rockwork.
he's very shy, if I get close to the tank, he hides.
roommate, girlfriend, and I have all seen him (and are confused)

do they normally turn black? (with yellow harry looking legs)

is this a bad thing?




I did some searching,
found these pics but no real info

 

[leebca]

I moved your post out of the Fish Forum in the hopes that those that keep invertebrates would be better able to provide info.

Good luck!

 

[Curtswearing]

The different species in the Mithraculus Genus have different colors and different shaped ridges on their backs. They can be green, red, black, brown, and even striped. Most species are safe when they are small however even everyones favorite, the emerald crab can become non-reef safe when large or when there is not much food.

If the ridges are less pronounced (i.e. smoother), then you probably are dealing with the Eriphia Genus. NOT REEF SAFE AT ALL

 

[Jan]

I used to have a black one like this in my nano, a hitchhiker. He was also very shy and only came out after lights out. Then I broke down that tank, moved the rock into other places and I haven't seen him again. In my opinion, he was harmless...especially in comparison to some of the other mithrix crabs I have purchased which ate things I didn't want them to eat.

 

[loohunter]

i have a red one that was a hitch hiker.i have no probs with it. i consider everything reef and fish safe until i catch them in the act of destroying something. i also feed alot so all my critters tend to leave stuff alone

 

[KrautBurner]

thanks guys,


I was just confused that I didn't find much info on "Black" ones
I'm not too worried about him,
he's very shy

and seems to stick to the same region of the tank, picking alge from the rock
never seen him near my Rich's or Zoa's

 

[KrautBurner]

so,

do you guys think it was a hitchicker or that one of the emeralds turned black?

 

[loohunter]

i would guess it was a hitchhiker but i dont know enough about them to say for sure. in my experience i have never seen any change color

 

[jamiehill]

I have a black one as well. I too bought a bunch of emerald crabs about 3 years ago to handle a valonia outbreak and all but the one are gone. It is about 3" across now, but also just sticks in the rocks all the time. I rarely see it and sometimes I think it has passed on because I won't see it for a few months then it sticks a giant claw out of the rock to grab some food.

I don't think it is a hitchhiker, but I am not sure. It looks like an emerald crab, just big and black. I named him Mongo .

 

[KrautBurner]

I don't think it is a hitchhiker, but I am not sure. It looks like an emerald crab, just big and black. I named him Mongo .

Telegram for Mongo ......

does he ride an ox?

 

[lizardarm]

It's a hitchhiker Russ. It most likely came in on rock from the Shark Reef. I've got three of them in my 120 and that's where all of my rock is from; it must be an Indonesian thing. I've noticed them to be seemingly harmless so far; but as stated above, they can be harmless and suddenly get not-so-harmelss without warning after they reach a certain size. Mine have become less shy as they've grown and are now out during the day also, ableit only in the shadows, so I'm thinking that they will eventually get moved to the fuge. Try feeding it with a pair of tongs.

 

[KrautBurner]

cool,

thanks.



I saw him out today for the first time in the light.
I don't mind him (so far)