got ethical husbandry?

Hitchhicker Crab

Euphyllia

Euphyllia

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So last night I looked at my maidens hair which I am keeping in a small "breeder box" thing and saw that most of it was gone. It looked like it was dieing so I removed it and shook it off and placed it back in. I thought I saw a giant copepod in there but I'm squeamish and I decided not to look. I looked again this morning and saw it again. I looked closer and ti was a little, clear-blurry white crab. Not a pom-pom crab, possibly a vegetarian. The maidens hair came from Ocean Treasures. The crab is less than 3/4". What is it? Is it good or bad? Will it harm anything? If it's bad, how do I get rid of it? :~
 
Hmmm...No clear/blurry crabs come to mind. Emerald crab? Anemone crab?

I had a mystery crab about the size of a half dollar hitchhike its way into one of my tanks and it started hunting my fish. It had one really big claw and one normal sized one... I would watch it under the moon lights and it would creep its way towards a fish and then try to grab it. Pretty interesting to watch but a dottyback disappeared and I started seeing clamp marks on a few of my other small fish so I decided to take it out. No joke, catching it was a bit of a pain. First had to figure out which rock it was on, then pulled the specific rock out of the tank. Of course, the crab buried itself somewhere in the piece of LR so I prodded it out with some chopsticks...


It's probably harmless unless you see signs of it attacking your fish or other inverts
 
I had a small light colored crab stow away into a large tabling acro colony. He lived there for a very long time, iding in the branches and nibbling on bits of this and that. Watch your crab and if it begins waving feather-like front legs in the current, it may well be a filter feeding porceline crab. Otherwise, your guess is as good as mine. :O
 
Look at the claws themselves... do you see two little plates at the end of the claws? That usually points to them being "algae" eaters (with caution)

bad one (look at the pointed tip lacking the "plate" I was talking about)
CrabGreenStreaks.jpg


now look at this Mithrax crab that eats algae... notice the two little "plates" on the end of the claws?
25863_400wh.jpg
 
nudibranch said:
I think it is an emerald crab because of your description of it having one large claw and a very light green brown body.
Click to expand...

Mithrax have two same size claws FWIW so that would be a no given his description ;)

emeraldcrab1.jpg


Mithrax also have many other color morphs... white, black, red, and orange to name a few.
 
I've got a crab that came in inside a rock. He's white and looks hairy/spikey and has gotten pretty damn big (maybe 3" across). Any ideas?
 
Picture please. Most Id's can't be done via a couple descriptors :) hairy usually means bad, but is not a true way to ID them alone.
 
Pictures are essential. Those descriptions are way too vague to make any kind of educated guess as to what the crabs are. Ya gotta remember that there are thousands of possibilities.

I know reefers use "hairy", "black-tipped claws", and "pointed claws" as synonyms for bad. That's a really wide spread belief but it isn't accurate. The majority of crabs with black-tipped claws are xanthids & their relatives. Many of these - including some common hitchhikers - are primarily grazers on microalgae like dinoflagellates and their secondary food sources are worms & small crustaceans. If they're well fed they won't bother corals or fish. Pointed versus blunt tipped claws has no correlation with predatory or vegetarian. Being hairy is not a reliable indication of predatory behavior either.

Another problem in the hobby is the way LFS keep expanding the definition of Mithrax. I've shown pictures of various crabs listed as Mithrax on reef sites to some of my crusty friends and they either start laughing or sneering. For example, black Mithrax are usually Chlorodiella nigra - in the family Xanthidae - while the true emeralds are Mithraculus sculptus in the family Mithracidae/
 
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