[Penguin]

I'm interested in hearing from anyone who has had long-term success keeping emerald crabs. I've tried them a few times and they never last more than a few months for me.

Also, they are supposed to be good for controlling bubble algae, but has anyone ever actually witnessed them eating it? I have plenty, but I never saw them bothering with it, and never noticed a decrease. Maybe I had the wrong species of emerald crab and/or bubble algae.

For those that have kept them long term, did you target feed them as well, and if so how often?

Don't feel you need to post if you saw your emerald crab catch and eat your damselfish, or something similar. There are already lots of threads about that. I'm aware of the risks they pose to small fish and inverts as they get larger, and I'm ok with it. Thanks.

[Roxy]

Hi Pen, i have had my emearld Crab for quite a while. I have bubble algae. But have not seen my crab eat it.....I have notice some are gone but then i would get more algae coming back...I think what is happening is that he would grab it and it would burst into the tank making more bubble algae. so if you careful remove it yourself, without busting them you can control it too..hope this helps.

[-=dieseldave=-]

I have watched several emerald crabs eating bubble algae. I have yet to have success with keeping them alive past 6 months.

[Reefland]

I have kept them for short periods of time, <6 months. However when I had them, I noticed a decrease in Valonia.

[Penguin]

Thanks for your replies. When I last tried them I had lots of red bubble algae and some small green bubble algae (not Valonia, I think). They never really touched it. I think maybe there is some food item they need that is not present in at least some of our tanks. They should live longer than a few months IMO. I'm reluctant to try them again...but that darn bubble algae is a problem.

[mistermikev]

I am surprised... I thought I was the only one with emeralds that lasted less than a year. I've never gotten them again. If possible, remove the live rock with bubbles, rip off all of them and pop the rest, then wash the rock in saltwater to get rid of the spores. I had bought a rock with bbl algae on it and got rid of it for good by doing this. that was 1.5 year ago... no return.

[Ninong]

Originally Posted by Penguin

Also, they are supposed to be good for controlling bubble algae, but has anyone ever actually witnessed them eating it? I have plenty, but I never saw them bothering with it, and never noticed a decrease. Maybe I had the wrong species of emerald crab and/or bubble algae.

I have read reports on the boards posted by hobbyists who say they witnessed emerald crabs (Mithrax scupltus) eating bubble algae.

In their natural environment, I believe these crabs are primarily herbivorous as juveniles but become primarily carnivorous as adults: "The emerald crab, Mithrax sculptus occurs among the branches of the coral Porites furcata and feeds on the polyps at night. It has also been observed to feed on organisms attached to seagrasses (Colin, 1978)."

As with any marine animals that we keep in our tanks, their natural behavior, including feeding habits, may change to adapt to the conditions they find themselves in.

Perhaps if you had a generous supply of Porites furcata in your tank for the crabs to feast on, they would thrive? Of course it's always difficult keeping the prey item alive in such situations.

[Penguin]

Thanks Ninong. I was wondering about their natural diet.