Emerald crab question
 

I am having something of a bubble algae bloom. I understand that Emerald (Mithrax :question: ) crabs will eat it. Has anyone found this to be true? What else do they eat? Are they really "reef safe"? Will other desirables in my tank disappear?

TIA.

I had the same question last month, I was cautioned that it was a hit and miss with the emarald crabs, but they are safe with reefs.

I saw mine puncturing the bubble and devour a few bubbles the very next day, but I did not see the algae population go down.

Everytime I get a chance to dip my hand in the tank, I scrap of a portion the bubble algea that is visible, and I later siphon the debri that settles to the bottom. I wear gloves as I have a couple of 8" bristle worms in my tank.

HTH

They're definitely hit and miss! None of mine touch bubble algae, but they are great at eating other types of algae.

I'd recommend getting a couple of them. Even if they don't eat your bubble algae they're still great scavengers.

I like them. I make sure I have at least 1 and usually 2 in my tank at all times.

I just read a thread on RC where the emeralds attacked and killed most of this guy's fish! He witnessed the attack in person! :eek:

http://reefcentral.com/forums/showth...hreadid=256421

They do attack my fish when they are dying. The fish were doomed regardless of the crab in my case (not that I lose a lot of fish but once in a while, I lose a goby here and there when they don't eat and starve). I suppose it is possible for them to kill live healthy fish but that must be a large crab. Hard to imagine a tiny emerald taking down a decent size fish.

I read that last night too.. Scary.. that poor fish.. and was strange how the guy did nothing.. Usualy if I turn on the lights it frightens the crap outa my crabs..

Chad

OK, I just read that thread. My opinion is that there is no way an emerald crab in his photo could take down and kill a healthy tang. That fish was sick and the crabs took advantage of that. Fish will usually die at night anyways. That is when CO2 is at its highest and O2 is at its lowest. When I kept freshwater fish and a fish would die, I usually found them dead in the morning. Now, was there a chance that tang could have recovered if there were no crabs? Possibly, but who knows.

Sam, I disagree. I think that if a crab got a good hold of a fish's tail, it could hang on and immobilize the fish. The fish's injuries did look like they could have happened thrashing on the rocks. I once had to remove a crab from th emouth of one of my triggers...it was major surgery outside of the tank!! I ended up needing to crush the claw with pliers to remove it!

The guy said he had *6* emerald crabs in his tank and absolutely no algae...

Don't you have to feed ALL your livestock - crabs included? If there isnt enough food around, is it possible the emerald crabs can go after a meal they normally would not go for?

Just speculating, I dont have emerald crabs yet...