So, are Emerald Crabs reef safe or not?


Is the verdict out on these guys yet? I was led to believe tht these guys are an asset to a reef set up. In particular with their means of controlling bubble algae. I have however been noticing some damage in my reef. Sarfish limb severed and fish damage. The culprits are either the emerald crsb or puple reef lobster. I seem to think that it is the lobster. In any case I am curious to know it i can be reassured that the crabs are fine in my set up, particularily with all my beatiful & unusual forms of mushroom anenomes. Thanks TT. :eek:

nm reef

Active Member
teetee...all I can tell you is that I have 2 emeralds in my reef along with an assortment of 'shrooms and date the emeralds have never bothered anything('cept for munching algae)....from what I've heard I'd be keeping an eye on the lobster....but as for the my opinion and experience they are fine


I have three emerald crabs at the present moment in my 55 gallon reef tank. I have had them currently for 2 years and they were placed in my tank for algae control. They have been incredible, they have eaten all my bubble algae. I admit that I was a little worried when I placed them in the tank, due to there huge claws. But after watching them munch on algae, I feel that they are an asset that ever hobbyist most have in their tank.null


I too would suspect the lobster over the emerald. Never had a problem with emeralds in the past.


Active Member
Gosh, we love our little green emerals, they are to cool to watch, and ours have never hurt anything. They help keep the algea from building up. Lisa


Ive got one in my 10 gallon long and he only
eats the green stuff. Never seen it bother
anything else in there.


Active Member
I've never had a problem with mine either. I've got 3 in a 55gal reef. I've seen them walk over a green star polyp colony and clean around them, but never nip the polyps themselves. I've actually been thinking of getting a couple more because I still have some bubble aglae.


Havnt figured out who it is yet, but something munched a couple of tips off my xenia. Nothing too bad as I have enough of it, but other than this, the emeralds have not done anything. Only crab I have had problems with are the sally lighfoots.


hello, I have two emerald crabs and one is extremely aggressive. It tried to munch on my tree coral, using its claws holding it. One time it tried to attack my seabae anemone also by its claws holding the tentacle. I am hoping to catch him and put him in a smaller tank. I wonder if I don't have enough algea for them to eat, even my brittle stars tried to get my corals at night. The other emerald is fine, because when I bought him from this site, he arrived without claws :D


New Member
I think the emeralds are fine if they have enough to eat. I feed mine dried seaweed on occasion because they started nipping at my button polyps and they will eat that coralline algae we all love so much.:D


Active Member
I have tons of em. Emeralds are one of my favorite additons. They are also constantly eating. Great cleaners. Fun to watch too. :cool: