Are emerald crabs killers?

[TonapahNorth]

I have 2 emerald crabs in my tank. Over the last month, they have eaten a damsel, a sand sifting star, and now they have eaten my Midas Blenny.

My water parameters have all been perfect. Ammonia is zero, nitrates are zero, phosphates are zero. Yesterday, the blenny was acting fine. He was eating everything in sight and swimming freely in the tank as he usually does.

This morning he's completely gone. I am merely assuming that the crabs have eaten them entirely. But he is gone.

Any thoughts? I'm worried that my crabs have become a little more aggressive and hunted the blenny in his hole.

 

[Small triggers]

Are they really big? Sometimes they start hunting as they get larger because they no longer filter or eat detritus...pull them out and throw em in the sump ...

 

[glb]

I have 2 emerald crabs in my tank. Over the last month, they have eaten a damsel, a sand sifting star, and now they have eaten my Midas Blenny.

My water parameters have all been perfect. Ammonia is zero, nitrates are zero, phosphates are zero. Yesterday, the blenny was acting fine. He was eating everything in sight and swimming freely in the tank as he usually does.

This morning he's completely gone. I am merely assuming that the crabs have eaten them entirely. But he is gone.

Any thoughts? I'm worried that my crabs have become a little more aggressive and hunted the blenny in his hole.

I've wondered about this myself. I lost a few chromis and clownfish suddenly and I've wondered if the crabs got them when they were still alive. I used to see them snapping at the fish. Emerald crabs have been relocated.

 

[Birddog]

My $0.02... it depends on the size of the emerald crab. I have tried these little son-o guns for several years to control bubble algae. Buy them small and the really can't get the job done, buy them larger and they are voracious eaters of anything they can get a claw on. Once the bubble algae is gone they'll pick you LR clean of green algae. Once the LR is clean they'll stick their claws in the mouths of LPS (causing a lot of damage to the LPS) especially at night after feeding these corals mysid. In the last month I've had one try to (unsuccessfully) take my Ocellaris out. The Clown was banged up pretty good but survived the ordeal.

 

[TonapahNorth]

Interesting.

My two emerald crabs are smaller than dimes but I don't know how big they get or how old they are. I've never had algae problems and I keep the tank pretty clean. Maybe I'm starving them and they have resorted to hunting.

I just got them as part of my first clean up crew ever. I only started in the hobby about 45 days ago. So I'm beginning to wonder if the crabs are a bit vicious or what.

 

[Salty Dog]

when your starving you eat anything, remember that, other than that feed your fish, emeralds snails ect will clean up the rest

 

[Pappy]

Can't say that I've had any kill fish (luckily they're not expesnsibe fish you've lost so far) however I've caught them pulling on zoas in the past. Get them out all crabs are bad ime except blue legs!

 

[nazzman]

Dry seaweed sheet on a rock or clip along bottom feeds my fish and my crabs I have 2 big emeralds and they swipe at fish while feeding on it