Emerald Crab devouring acro

rblackmon89 · Mar 31, 2021

So today I literally sat and watched as my emerald crab destroyed about 1/8 of a new acro I got a few days ago.
This wasn’t merely the crab scraping off dead tissue either. This acro had great polyp extension and seemed quite happy. The crab had crushed the skeleton to the point there was an abrupt cliff on both tips of the frag. Needless to say the emerald is in timeout now.
I did some extremely brief digging and couldn’t find too many cases. Just decided to post in case someone else has some random chunks out coral missing and no other culprit was thought of. Fun stuff!

Doctorgori · Mar 31, 2021

appreciate the sample .... just more data “never trust a crab”

MasonK24 · Mar 31, 2021

ive had this happen more than i can count. i like to think it was a mistake by the crab but after the 4th time (4 different crabs not 4th time by the same crab) it was blatantly ripping polyps off my sps/lps i will never add one to my display ever again. no way.

RedReefer · Mar 31, 2021

I quit with emerald crabs in a display about 10 years ago. Similar experience with crabs and sps. Crabs will steal food from coral and irritate coral when crawling on them.

rblackmon89 · Apr 1, 2021

This was my stepping stone to learn that! I thought it was crazy that this thing was just carving through the skeleton. Good learning experience, and I’m glad I caught it actually happening so I know exactly what was going on...

Reef_Colors · Apr 1, 2021

Happened to me also. Bought an emerald crab to help with bubble algae, i had mats of it growing everywhere. I put him in and he started with some bubble algae. The next day he was chipping off the top of an acro frag. Sent his a** back to the lfs.

rblackmon89 · Apr 1, 2021

No fun! They’re such cool critters, so unfortunate. Just for my own knowledge, does the “no crab” rule cover hermits too? Or is that a separate debate on its own?

MasonK24 · Apr 1, 2021

rblackmon89 said:
No fun! They’re such cool critters, so unfortunate. Just for my own knowledge, does the “no crab” rule cover hermits too? Or is that a separate debate on its own?

ive personally never had hermits bother any coral besides the occasional bumping into to.

RedReefer · Apr 1, 2021

MasonK24 said:
ive personally never had hermits bother any coral besides the occasional bumping into to.

Same here hermits are not as bad, but they will steal the food from the coral if they are near at feedings.

Jud · Apr 1, 2021

Same thing here! Put one in to deal with some bubble algae. 20 minutes later I’m seeing pieces of neon yellows and greens in his claws as he tears apart hunks of my fascination favia. No thanks!

Brit’s Fish · Apr 1, 2021

Same here! I just had one do this two weeks ago. She wasn’t in the tank for more than 5 minutes before she started eating my Xenia (which was fine tbh) but it was the chunk of my fox coral that did it for me. She was in time out before I even threw the bag she came in in the trash.

Calm Blue Ocean · Apr 1, 2021

Doctorgori said:
appreciate the sample .... just more data “never trust a crab”

Or a shrimp as I recently discovered. Peppermint shrimp had been in the tank for over 10 months trouble free, then I caught her eating my brand new birds nest. Tastes like aiptasia?

Fish Think Pink · Apr 3, 2021

rblackmon89 said:
So today I literally sat and watched as my emerald crab destroyed about 1/8 of a new acro I got a few days ago.
This wasn’t merely the crab scraping off dead tissue either. This acro had great polyp extension and seemed quite happy. The crab had crushed the skeleton to the point there was an abrupt cliff on both tips of the frag. Needless to say the emerald is in timeout now.
I did some extremely brief digging and couldn’t find too many cases. Just decided to post in case someone else has some random chunks out coral missing and no other culprit was thought of. Fun stuff!

Think emerald crab killed 2 gladiator snails 2 weeks ago. Its the only thing in my tank that has strength to have ripped 1 of 2 in half, giving clue to why snails died. BF really really wanted crabs for bubble algae (Vibrant instead was solution).

20+ years ago had tiny lobster kill fish 15 times its size, so didn't want these crabs... now I'm even more worried for my coral babies...