# Marine Aquariums > Nano Tanks >  Any one no what sort of crab this is?

## lost

I think i have about three of these in my tank i did try to catch one to get a better picture but i put the mussel in the glass came down the next day and the mussel had gone but no crab :oops:

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## Timo

Could be a emerald crab, normally not to much of a problem and quite reef safe  :Smile: .

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## lost

Thank you mate thats good the only time i have seen them out is to scavange at the rock adds a bit of life to my tank

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## Timo

He will eat the caulerpa in your tank. If you look at the stuff on the right you can actually see the little pincer marks were he's had some.

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## lost

I see what you mean thats not such a bad thing that stuff is spreading like anything

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## Gary R

It looks like a emerald crabs to me as well, they are a member of the cleanup crew m8 they scavenge the aquarium for leftover food or algae and help to keep the aquarium clean. One of their claims to fame is that they will eat bubble algae (valonia) which is a nuisance hitchhiker on live rock from time to time. here is a picture of one of mine

Attachment 171

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## lost

Thanks gary i think i will leave the little critters there and see how things go i wonder if me peppermint nicked me crab bait :roflmao:

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