Crab? What kind? Good or bad?

[Susanedw]

Any idea what kind of crab? If not a baby emerald, it had to come in on a frag and survived a coral dip

 

[DaveK]

No doubt it came in on some live rock or a frag. At this size I don't think it's a problem. A couple of things to look for in crabs to determine if they will be a problem. Look at the back legs. If they are paddles rather than regular legs, it's a swimming crab, and those tend to be problems. Look at the claws. If they look like they are for grabbing, they tend to be problem crabs. Look up an image of a gorilla crab and you'll see what I mean.

Even if the crab doesn't fit into one of those two categories, it can still be a problem. Crabs are feeders of opportunity. If they can catch it, they will eat it.

 

[Susanedw]

Still trying to get a good daytime pic. So far I've found a possible coral crab as a closest match

 

[melvis]

Agree 100% with what DaveK said, have had problems with similar.

In fact, I was sure there was still a crab hidden in mine somewhere and now I'm convinced - my Coral Beauty has vanished so I'm assuming he's been a very expensive meal for the crab. :-(

If it does have paddles, the old glass jar resting against live rock with a prawn in it won't work - as it'll swim in and out. You'll have to catch via other means, and probably at night.

 

[Susanedw]

Waiting to see it again. Right now, it is very tiny, probably size of my pinkie finger nail. From a distance, it looks just like a white spot on the coral. Didn't see last night. If it is a coral crab, it is somewhere on that frag as they stay on the one coral all their lives unless they find a mate and move to another coral. Fingers are crossed it is that type of crab as they are considered one of the good guys