Live Rock Crab Question...

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SkinnyPete

Aquarium Advice Freak
Joined
Feb 4, 2005
Messages
494
Location
MA
So, I got so many critters with my lr from lr.com. They are so cool to watch that I haven't really removed anything except an isopod and a few worms.

My question is, I have a TON of crabs - some pretty large, and 3 urchins. I'll take a pic of the urchins but its the crabs that I'm concerned with. They haven't touched any fish or shrimp so far so I don't really think they're a threat to them, but I'm thinking that I might be losing snails and maybe even featherdusters. Also, ever since the crabs have felt comfortable enough to wonder the rocks during the day picking at it constantly - my coraline algae has really regressed. My Alk/CA seem fine. Maybe its a weird coincidence, but is it possible these crabs and/or urchins are feeding off the coraline? Will these critters be a threat to anything else and should they be removed? And, lastly (i promise), how do I tell a good crab from a bad one?

- Skins
 
Haha. I knew that was going to be asked. I don't really know how to describe them. They are pretty much all green, hairy legs. No black tips on the claws. Some of the smaller ones seem to have tiny white stripes on their legs. The really big one has a head about an inch and a half wide and really big claws - the size of him kind of scares me and I've been trying to catch him with no luck.

While I'm at it - the urchins are black they've grown probably 3 times their original size in about a month.
 
I'd keep working on removing the crabs. Even the good ones have the potential to become a problem as they grow. See if your lfs will take them. As for the unknown urchins, they aren't so bad. I believe you'll find them listed as common urchins or purple urchins. They are clumbsy and eat some coralline but, not a terrible hitchhiker. The grow extremely fast but max out at about four inches in diameter. That's including the spikes of course. I ended up with 13 of these. I gave some away and sold some to my lfs. I kept one and he's been in my tank for at least three years.
 
call Mike at liverocks.com. He is more then helpful in IDing hitch hikers that come in on their rock.
 
Fluff, yeah that's the kind. Thanks.

Lando, great idea. Mike was very helpful when I first got the rocks - I'll shoot him an email.

Thanks all.
 
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