Mithrax / Emerald Crab Feedback

[g_langley]

Yesterday I purchased a small (1.5" span) mithrax crab to clear some bubble algae and other green stuff.

The only fish I have is a jewelled blenny who keeps a fighting conch and 6 turbo snails company.

I know that crabs are opportunistic and would like other peoples experience on this little guy. When will he be big enough to pose a threat to my blenny who is approx. 4 inches long?

Thanks

[murfman]

how big is your tank? IMHO if you keep the crab fed and healthy, you should have no problems.

[mwwhite]

We have one rather large emerald and one small one in a 72. We've had no problems with them at all. We also have 5 fish in with them and numerous coral. Everyone gets along peacefully.

We had a terrible bubble algae problem. Got the crabs a couple of months ago now and the bubble algae is GONE!

They are also entertaining to watch.

[g_langley]

Sorry, It's a 35 gallon tank with 40 pounds of live rock.

[murfman]

they should be fine together.

[UnderCoverDork]

i have a 20g w/ 60lbs of LR and 1 Emerald crab. The crab will not bother anything

[techreef]

i have a ruby crab (red emerald crab) in my 90G tank. i've watched him clipping off polyps from some hitchhiking SPS corals that I have in the tank. i'm battling cyano too, so I believe that I'm overfeeding, which defeats the whole "keep them well-fed and they are not trouble makers" theory. i've had to harrass him away from the corals a couple times. i haven't caught him bothering the corals in about a month, but honestly i'd rather just have him gone. long story short; there's just no 100% safe answer to crabs. i can't pin the death of a tiger goby on the ruby crab as i also had a hulking gorilla crab (since captured and removed) in the tank during the goby's disappearance. my ruby crab is about an inch across his carapace. the gorilla crab was an easy 2" across.

[Bobby A.]

i have 4 emralds and a ruby crab that is kinda big in my 75 gallon. i also have a med. sized long spine urchin. the other day the ruby was breaking off spines from the urchin and eating them like a pencile sharpener.... but the urchin got away.... that is the only problem i have had with them.

[grouper25]

Dont let anyone ever tell u that Emeralds dont destroy everything.
I had one that got huge and ate everything in my tank, including invers and coral. The rat finally died. I could never catch him as he was lightening fast.

[GobyJohnKenobi]

Like almost everything else they will get hungrier and more aggressive as they get bigger. And you will need to watch them more.

[techreef]

the other day the ruby was breaking off spines from the urchin and eating them like a pencile sharpener

holy smokes. that's a new one!

[Frick-n-Frags]

yeah, this debate is as old as the sandbed vs no sandbed one

I have always had the best of luck with them. They clean very closely around the corals and at times seem to find something on the coral, but the corals all do better from the attention.

My only beef is they throw stuff off the cliff at night and I have to find it and put it back. I also only get the green ones (well sometimes with white and or black in them but they are all basically the green ones)

there are also several species of mithrax and that probably doesn't help with the confusion.

[Slamajama]

emeralds r algea eating machines...but when algea is gone they may feast on sps

[aaron112977]

Take him back now i had two they told me were reef safe and i have plentry of buble algae but no they liek to eat a a 40 dollar alovepora and a yellow colony polyp

[davidhughes85]

There have been lots of reports of these guys causing a lot of problems bothering fish when they get bigger...but some dont...depends if You want to take a risk.