Has anyone seen an emerald crab do this to a coral?

[w2inc]

I have had some tissue loss on my corals for just over a week. I thought it was all kinds of things from new adjustment to lights, alk, something falling in the tank, medicated cream not washed off my hand, pH swing, and on and on. For some reason I normally pull back on food when things don't look right.

I thought I had it beat and I woke up to find this. I just put a bunch of emerald crabs in the system to go after my bubble algae. I have seen them picking at corals, but I have never seen them do much damage. Any thoughts?

 

[Angel_Anthias lover]

Its possible, people have reported them snipping of euphyllia heads for the fun of it, so its likely they cpuld have been the culprit, wpuld there be anything else in your tank who would do it?

 

[wesman42]

I have personally observed emerald crabs going after monti caps in a similar destructively fashion.

 

[AZG]

Yeah my emerald took out my torch. He’s no longer with us now.

 

[w2inc]

Its possible, people have reported them snipping of euphyllia heads for the fun of it, so its likely they cpuld have been the culprit, wpuld there be anything else in your tank who would do it?

There is an Acropora crab living in most of those colonies. I see them dig into a polyp now and then but have never seen any damage. If anything, I thought they would defend their turf. As far as predators or bugs, no. Not really any reason to think I might have introduced one either.

 

[w2inc]

I have personally observed emerald crabs going after monti caps in a similar destructively fashion.

Similar meaning taking out patches like that?

 

[w2inc]

Yeah my emerald took out my torch. He’s no longer with us now.

Did you see him messing with SPS? Do you think it would make a difference? I know they will pretty much eat whatever is in front of them.

 

[Tuan’s Reef]

I didn’t have sps in my tank at the time but a new emerald I got went straight for my hammer. He’s no longer in my system . No emerald crabs will ever touch my system again intentionally.

 

[Angel_Anthias lover]

There is an Acropora crab living in most of those colonies. I see them dig into a polyp now and then but have never seen any damage. If anything, I thought they would defend their turf. As far as predators or bugs, no. Not really any reason to think I might have introduced one either.

Is it a good acropora crab? As in is it hairy or smooth like a porcelain crab

 

[vetteguy53081]

yes- emerald crab- I don't trust mainly the males

 

[CenlaReefer]

I had a larger red mithrax that was a terror, eating multiple corals. It ate GSP and 2 different LPS corals... never SPS. I have never had trouble with small emerald crabs.

 

[w2inc]

Is it a good acropora crab? As in is it hairy or smooth like a porcelain crab

All the emeralds I have are small right now. I did cut back on feeding the system just before the attack in the photo. My Acropora crabs are pretty big and have been breeding. They are smooth. The birds nest holding this one stopped losing tissue when I turned down the lights. I thought things were over with and then the purple one had the big bald spot show up overnight two days later. I feel like it is the emeralds. I am going to start overfeeding the tank again and see if it stops.

 

[Angel_Anthias lover]

All the emeralds I have are small right now. I did cut back on feeding the system just before the attack in the photo. My Acropora crabs are pretty big and have been breeding. They are smooth. The birds nest holding this one stopped losing tissue when I turned down the lights. I thought things were over with and then the purple one had the big bald spot show up overnight two days later. I feel like it is the emeralds. I am going to start overfeeding the tank again and see if it stops.

Ah ok hes a pretty crab (or she)

 

[w2inc]

Ah ok hes a pretty crab (or she)

That was she. She is holding roe. Her man lives in and around the coral that has the bald spot on it. After lights out he stays on the damaged coral. He is either eating at it or protecting it an I am not sure. They all kind of scrape at polyps but I have never seen actual damage. I was up late last night and was able to catch the both of them and pull them out. (and do a lot of unintentional fragging). I found one emerald picking at a coral and she let me grab her without a fight.

They are living in another tank while I see what's up. I will check in if that fixes things.

 

[Retroreef]

I just finished dealing with this same issue this week!!! I added 3 emerald crabs to my sps only system and they did some damage just as described. Took patches out of jf flame cch purgatory rainbow monti wwc heartbreaker. All this damage was done in 4 days or so. I got 2 out and the other lost a claw in an attempt to remove then got the last one out a day later

 

[marlinmon]

I have had some tissue loss on my corals for just over a week. I thought it was all kinds of things from new adjustment to lights, alk, something falling in the tank, medicated cream not washed off my hand, pH swing, and on and on. For some reason I normally pull back on food when things don't look right.

I thought I had it beat and I woke up to find this. I just put a bunch of emerald crabs in the system to go after my bubble algae. I have seen them picking at corals, but I have never seen them do much damage. Any thoughts?

Yep! I’ve got two of them that pick on that same exact coral and any other of my cheap SPS. I watch them do it all the time. The stuff grows so fast that I usually don’t worry about it.

 

[Diznaster]

Yes I had one that would literally only eat SPS even if I had algae or put shrimp out for it. If I moved it's favorite coral, it would be on the other side of the tank eating again it the next day. Good luck catching it, make a trap and put the coral in it. You'll find it in the trap soon after.

https://www.reef2reef.com/threads/emerald-crabs-are-not-reef-safe.481132/

 

[jjam]

Same here. Im on the hunt for one of the emeralds in my tank that was going after SPS. I checked the tank one night last week and he was hanging upside in a acro tearing the flesh off. I've almost had him twice now.

 

[Prime Coral]

All the emeralds I have are small right now. I did cut back on feeding the system just before the attack in the photo. My Acropora crabs are pretty big and have been breeding. They are smooth. The birds nest holding this one stopped losing tissue when I turned down the lights. I thought things were over with and then the purple one had the big bald spot show up overnight two days later. I feel like it is the emeralds. I am going to start overfeeding the tank again and see if it stops.

Hi there
I see little bugs on your branches and they look like red bugs

 

[Prime Coral]

I have had some tissue loss on my corals for just over a week. I thought it was all kinds of things from new adjustment to lights, alk, something falling in the tank, medicated cream not washed off my hand, pH swing, and on and on. For some reason I normally pull back on food when things don't look right.

I thought I had it beat and I woke up to find this. I just put a bunch of emerald crabs in the system to go after my bubble algae. I have seen them picking at corals, but I have never seen them do much damage. Any thoughts?

Some of the other corals in the photos are showing tissue loss as well.
https://coralrtn.com/signs-of-infection/