Gorilla or emerald? Or worse? Id help please!!

Home Forums General Marine Keeping Discussion Fish and Invertebrates Gorilla or emerald? Or worse? Id help please!!

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    Hi all, I need to know what to do about this situation, and if this crab is emerald/gorilla/worse?

    I have seen in my tank this crab, similar size and shape as emerald crabs, I have had emeralds in past but they went missing or died, so this could just be the return of one of the emeralds.

    However my snails have been randomly dieing and I caught this crab eating one. the other thing that is strange is this crab like to borrow under the rocks and keep low to sand bed.

    This crab is also a whiter colour then emerald, but could this be due to a malt?
    The crab also has slightly darker tips to claws, not black like a gorilla but a brownish tip.

    So my question is do emerald crabs borrow in sand? Can emerald be a whiter colour and have brownish tips,if so safe to say it’s and emerald and leave in tank?
    Of not what could it be and how do I try and get it out baring in mind that it’s mostly at sand bed level or under rocks? Any help greatfully recieved!


    I really Chang see it too clearly but if you get a good look at him , count his legs .
    It sounds daft I know but an emerald isn’t a true crab so it would have 6 proper legs plus it’s two claws.
    A gorilla crab will have 8 legs, plus it’s two claws .


    The guy at my LFS reckoned that an absolutely spotless tank with no nitrates or phosphates would soon starve Xenia and eliminate it.

    Personally I reckon he’s talking rubbish. But you may want to give it a go, because in my experience a strip down and rebuild with new rock is the only thing that works, and even then any reintroduced coral is a risk.


    Thankyou very much, that’s a peice of info I have been looking for! Il have a little look, I tried hooking him out yesterday, and failed, but I may of berried him and or blocked his entrance, don’t know if he will survive anyway?

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    Just looked on Google, there are plenty of pics that show emerald crabs with 8 legs, so not sure that theroy is going to work?

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    Make a bottle trap and bait it with some food. A small pop bottle with the top cut off and inverted should be fine, and place it near it’s hole, sunk into the sand a little. It may take a couple of goes but they usually work. You won’t have killed it by burying it I’m fairly sure, patience is the key when hunting! Once you’ve got it you’ll be able to ID it . Good luck with it.

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    He is not an emerald crab (Mithraculus sculptus) IMHO. The claws are wrong and also they have smooth claw apendages vs the very textured ones in the pics.

    I would say it’s a close match to a xanthidae, probably one of the gorilla crab species. Difficult to say what he’s feeding on. Could be algae, could be snails or coral. They are always a risk and not considered reef safe.


    Yes, a piece of frozen shrimp, not a whole one. If you think it’s too big to go in the standard bottle opening you can cut that off to a point the hole is big enough, bear in mind they can get into quite small places. If it doesn’t work one night replace with a fresh piece the next night.

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