Emerald Crab Reef Safe?

[Burrito]

My guy last night. Gonna take him out next time he’s in the opened. I think he’s too big and doesn’t eat algae. Just swipes at my firefish. Doesn’t bother coral but is so big that he knocks stuff over all the time.

 

[YHSublime]

I have one in a 96 gallon tank. It has found a natural cave under a large acan. I have 4 acans with mutiple heads, a frogspawn, a large brain coral, GSP, and a few other LPS. My crab has been a model citizen. I do spot feed his acan home and he eats when I do that but there has not been an issue and I've had him at least 5 months. As long as there is sufficient food to eat I think the crabs are well behaved. But if they get hungry any reef creature may become unsafe.

Same here.

I've got a big ol' dude affectionately named Hercules. He's gigantic, and opportunistic. He'll take food out of my flower rock nems. He'll pick at things, like SPS, but they'll scrunch in polyps, and he'll move on. Also, picks at the rocks, and you know, bubble algae, so I'll take my chances. I have a hard time with people being like "my emerald crab got my fish," mostly because I think the fish must have been in pretty bad shape for a crab to get it. Including people that think their BTA's are eating their fish as well. I think they are cool additions, and if they end up bothering you, or nitpicking at certain corals, sump em!

 

[Crimsonphoenix]

I have had 3 different emerald crabs and each one was great for eating bubble algae but then would go after my lps corals such as euphillia and my lobos..

 

[Jet915]

I caught mine picking at zoas so in the sump it went...

 

[Raypriceart]

I read that they like nori. Never seen them eat it though.

They love it!

 

[Maxi]

I caught my My emerald crab eating my OG bounce.

 

[choss]

interesting on the zoas. Mine lives under an acan with zoas on the same rock. All seem unaffected. Again, I believe it has to do with the availability of food. My guy has a ton of real estate to roam - not a lot of competition in my tank at the moment. Just a few hermits.

 

[JonJ]

They are hit or miss in my experience. I recently bought a pink emerald crab that molted within the first few weeks and developed gargantuan claws. Whenever I would feed the tank he would rush to my bubble tip anemone and take whatever food it had grabbed. Sometimes it would even rip tentacles off of it. Needless to say, he was donated back to my LFS! They are easy to catch so I would still try them, just be ready to take them out if necessary.

 

[MARK M. DAVIS]

My tank is SPS dominant. I have many >10 emerald crabs, also hermits and snails. The hermits kill the snails. The emeralds have done a great job on bubble algae. They've never touched an SPS coral or frag. I see them periodically eating algae or coraline algae. One is very large and see him here and there. They don't pick on fish. I have a pipe fish and he's fine. I don't have zoas or LPS so I can't really comment on that. Some die due to maybe fights with other emeralds or maybe even the Melanarus. Don't really know for sure.

 

[BigJohnny]

I had 2 emerald crabs. I saw one literally eating acro polyps, and one grabbed my midas blenny by the head when the midas tried to knock it away from his favorite hole. Left a mean scratch but it healed in a couple days. Not sure if it was just one crab or both but regardless there can be problems is my point.

I feed HEAVY 4x a day so available food had nothing to do with it.

 

[BigJohnny]

I had 2 emerald crabs. I saw one literally eating acro polyps, and one grabbed my midas blenny by the head when the midas tried to knock it away from his favorite hole. Left a mean scratch but it healed in a couple days. Not sure if it was just one crab or both but regardless there can be problems is my point.

I feed HEAVY 4x a day so available food had nothing to do with it.

Oh yea and they never touched bubble algae

 

[Oshengems]

I have one he’s huge!!! But this is my 4rd got them to take care of my bubble algae the females are poor clean up crew and they did not touch the bubble algae and the last one harrased my hammer until it died took them all out got a male he’s a bulldozer 24/7 grazing anything and everything even some codiom algae I was growing
, doesn’t bother anything else but he does takes swings at passing fish but I think he’s just a thug always trying to start something

 

[Cheche]

I did took my emerald back to the lfs I got him yesterday I see him eat Algee and look like he was picking on the edge of the corals but I keep watching and he did eat some of the coral so I did some research and it was more bad reviews about them. And just a few good ones and then read about them eating live fish and I was thinking about my clown fish they all sleep on the bottom of the tank easy target .. and I won’t let one 6$ crap eat 100$ Coral or 90$ fish .. for me is not worth it I keep my water change on a tight schedule to avoid algae boom . My opinion

 

[HarryC]

Bought one that was smaller than a dime last week. Caught him tearing the new flesh off my prized torch and eating it his second night in the tank. Tons of bubble algae and other stuff for him to eat.

 

[Losthawk69]

I have two emerald crabs in my Reefer 170. Both are very active. I put some new frags in my tank on a rack. They wouldn't leave the frags alone! Mostly picking at the frag plugs, but they completely molested a Hammer. I even moved the rack to a location where I didn't think they could get to it, but one figured how to jump from a nearby rock.

What's going on? I thought these were reef safe, am I wrong?

Mine was a jerk that was frequently trying to assassinate the royal gramma in the tank. He also consumed a chalice, sponges, and even some xenia. I'd give him nori and pellets, wouldn't touch them. He's also steal food from the rock flower nems. I don't trust them.

 

[Losthawk69]

I did took my emerald back to the lfs I got him yesterday I see him eat Algee and look like he was picking on the edge of the corals but I keep watching and he did eat some of the coral so I did some research and it was more bad reviews about them. And just a few good ones and then read about them eating live fish and I was thinking about my clown fish they all sleep on the bottom of the tank easy target .. and I won’t let one 6$ crap eat 100$ Coral or 90$ fish .. for me is not worth it I keep my water change on a tight schedule to avoid algae boom . My opinion

They will eat meat. No green algae then it's time to start feeding them I give mine at night small bites of shrimp small size of a pencil eraser they never touch my coral or fish but will if starving I guess. If I was stuck in my house locked in here nowhere to go I would probably eat the crab and the fish I don't know about the coral. But I use long tweezers send it on down where I see them with a flashlight.

 

[macinf]

I have two emerald crabs in my Reefer 170. Both are very active. I put some new frags in my tank on a rack. They wouldn't leave the frags alone! Mostly picking at the frag plugs, but they completely molested a Hammer. I even moved the rack to a location where I didn't think they could get to it, but one figured how to jump from a nearby rock.

What's going on? I thought these were reef safe, am I wrong?

I chased my emerald around for days after it ate a starfish and many other corals. Skewered it through its head. Other hermit crabs are beneficial.

 

[modom1207]

I read that they like nori. Never seen them eat it though.

Know this is an old thread but I caught mine eating some of my coral on day 1 (today). I took a pair of tongs and held a large sized piece of nori in front of him. He took it immediately. Devoured it within minutes. Hoping this resolves the issue. I don’t mind spot feeding as long as he leaves my corals alone

 

[formallydehyde]

Know this is an old thread but I caught mine eating some of my coral on day 1 (today). I took a pair of tongs and held a large sized piece of nori in front of him. He took it immediately. Devoured it within minutes. Hoping this resolves the issue. I don’t mind spot feeding as long as he leaves my corals alone

Try feeding him some meat-based foods as well. Dry is fine, just something like sinking fish food pellets/flakes or hikari crab cuisine if you really want to treat him. They're actually omnivores that lean towards herbivorous rather than strict herbivores and my suspicion is they need some amount of protein to keep them from getting rowdy. In my experience this keeps emerald crabs very well behaved but doesn't stop them from continuously grazing on algae.

 

[Crimsonphoenix]

I’ve had 5-6 over the years, always ending up taking them out because they ended up preferring eating frags…