Poll: are emerald crabs fish safe?

[mckinney0171]

I, personally, have no interest in eating coral. I might, however, if you starve me for a few weeks. Think of any reef-safe invert story that goes bad in this light... peppermint shrimp too.

tastes like chicken

 

[mfinn]

I added 3 emerald crabs to my 50 gallon tank ( for bubble algae) and 3 days later my yellow multibanded pipefish turned up missing.
The pipefish was my favorite fish and I had it in my 50 for 1-1/2 years.
I figure it must have grabbed it when it was sleeping and close enough to the rock structure to grab it.
A few zoanthid frags turned up missing with in a few weeks too. I found the cleaned off frag plugs back in the rock.


A few years later I tried them again for my bubble algae problem and the only fish in the tank was a desjardini tang.
They did a good job of cleaning out the bubble algae and had no problems this time.

 

[Bouncingsoul39]

I've never had them go after corals but this what I do just in case: I buy the absolute smallest ones I can find. Like nickel size. They are great for bubble algae. Once they get to about quarter size, maybe a little bigger, I would donate them to the LFS. My theory is that the smaller ones will be hungry and growing which is good for CuC, but have less potential for trouble making than the big ones.

 

[Reefaddict1979]

I put 20 in my 265 to combat bubble algae problem I used to have. I actually bought a rock with a beautiful chalice on it for almost free only thing is it was covered with bubble algae. 20 crabs and one rabbitfsh later and no bubble algae. Never seen them attack anything. And I agree this crab just isn’t capable of attaching a healthy fish.

 

[CNDReef]

I believe all crabs are opportunistic scavengers. As long as they’re eating they’re fine. If they don’t get there helping one day they’ll find it somewhere.

 

[mckinney0171]

I put 20 in my 265 to combat bubble algae problem I used to have. I actually bought a rock with a beautiful chalice on it for almost free only thing is it was covered with bubble algae. 20 crabs and one rabbitfsh later and no bubble algae. Never seen them attack anything. And I agree this crab just isn’t capable of attaching a healthy fish.

yup they are slow as can be. easy to catch too if you have to break up an emerald crab duel which I have in the past.

 

[Reefaddict1979]

I believe all crabs are opportunistic scavengers. As long as they’re eating they’re fine. If they don’t get there helping one day they’ll find it somewhere.

Of course they have claws. If hungry they can use them. But in a mature aged tank there should be plenty of algae and detritus for them to eat So they shouldn’t be a problem. I have no algae in my main tank. I mean if I put a rock covered in hair algae, my tangs and snails will pick it clean in 1 night. And still I see my crabs picking st rocks all day long. So they must have better eyes than me because they see algae lol

 

[C-Reefer]

I had a bryopsis outbreak so I got two in my 20 long. They cleaned it up fast, great CUC. Ate lots of algae and leftover food. I did find if you didn't feed them or they ran out of food they'd pick at my LPS, but that was rare. They both died very mysteriously about 2 weeks apart. Idk why as everything else was healthy.

 

[mckinney0171]

I too have had emeralds disappear and I believe it is mostly them killing each other over territory. Seems to me when I buy four or five of them I always end up left with just one big one at the end.

 

[ReefAddiction34]

I had a bryopsis outbreak so I got two in my 20 long. They cleaned it up fast, great CUC. Ate lots of algae and leftover food. I did find if you didn't feed them or they ran out of food they'd pick at my LPS, but that was rare. They both died very mysteriously about 2 weeks apart. Idk why as everything else was healthy.

Favia poisoning.... j/k

 

[Crabs McJones]

Had an emerald crab, no issues. I think as long as their well fed, they leave stuff well enough alone.

 

[tastyfish]

I have three emeralds, of various sizes in my tank (provided the pistol shrimp hasn't had them all).

They really helped rid the tank of a bubble algae problem and never touched a coral or another invert.

 

[CNDReef]

Of course they have claws. If hungry they can use them. But in a mature aged tank there should be plenty of algae and detritus for them to eat So they shouldn’t be a problem. I have no algae in my main tank. I mean if I put a rock covered in hair algae, my tangs and snails will pick it clean in 1 night. And still I see my crabs picking st rocks all day long. So they must have better eyes than me because they see algae lol

This is where I think a problem comes into play. You obviously have a large tank sinc you have multiple tangs, the OP has a 21 gallon tank that most likely will have about 20 lbs of live rock. How quickly do you think one crab could go through that rock?

 

[mostlysticks]

Fish? No way. Corals? Yes, that's a definite possibility. I had one that was a terror to acros. Yes, he was well fed.

 

[sfin52]

Have two in my 75 going to get some more. Never bothered anything and half of the time I can’t find them. I forget about them and there are waving and picking rocks. I believe they do it just to annoy

 

[Reefaddict1979]

This is where I think a problem comes into play. You obviously have a large tank sinc you have multiple tangs, the OP has a 21 gallon tank that most likely will have about 20 lbs of live rock. How quickly do you think one crab could go through that rock?

Emerald crabs typically do t wander too far in a tank anyway. Plus I wouldn’t advise putting 20 crabs into his tank but 2 in an aged 21 gallon would. Be ok

 

[ArowanaLover1902]

I've had good and bad, some that are zoa eating pests, some that seem to never eat any of my pest algae, and others who keep the tank algae at a minimum and cohabitate peacefully with all the inhabitants, I think it depends on the crab

 

[Kmsutows]

LFS suggested going with just female emeralds and I gotta say I completely agree with their suggestion. They don't get nearly as big and the few I've had in my reef haven't been caught doing any damage

 

[jda]

I saw this mentioned once or twice, but these are not detrivores... they cannot eat poo. They need real food.

 

[Ghxst]

Lots of bad stories are crabs sold as and misidentified as emerald crabs. There are many creatures in the sea, some look alike.