Cycle tank with lights on or off.

Tangster, don't tell me that!!! I have lots of feather dusters on my rock and I've seen tons of emerald crabs in there!!!! Should I try and get them out?

 

Ever hear of a shamed-faced crab or box crabs ? I have seen many of them come in on Live sand and rocks and wipe a tank out before they can be gotten out.. Never used a L/R or sand in my 30+ yrs and never had a problematic tank.
I had a tank once I set up at a local elem. school a teacher there thought a chunk of L/R was so beautiful and at 30.00 for the softball size rock she brought it to the school and stuck it in. Now this tank has ran perfectly for 5 yrs then one day fish starting to disappear well after a few more months I was told there was a beautiful crab in there and when had I put it in the tank ? It's soooo pretty I was told b y the teachers LOL
After tearing the tank down to get it I found a mantis shrimp and a few other crabs not to mention the other unwanted algae and aptasias and all.

I set up a tank once to give L/R and sand a try ' never again nope not me.. Its not what is on the rock we want its whats inside of it the whole premise behind the Live Rock and sand is instant tank set up so you could be sold more stuff faster..
If hobbyist truly understood the way bacteria's work then they would never use it. thats why it suffers die off of the bacteria.

All crabs and free hitchhikers are not bad or good its just one bad one can wipe you out. The Emeralds are fine as are the F/dusters But emeralds are all not totally safe either I have seen them tear up corals and when large enough to snatch smaller slower fish. All crabs are omnivores

 

Tangster what you think this crab is....lol He's in there as well.

 

sally lightfoot