New find In fish tank

[Bigworm]

Tonight we had some friends over so I cut my light back on for a few mim. to show them my tank. For the first time I noticed a little brown fuzzy crab. Is he ok to stay in the tank or do I need to remove him. He must have came in some live rock I bought a week ago. One more ? I have notice some very small critters around my sand bed look like little fleas or shrimp Does any one know what this is. Thanks WORM

[zhenya]

I'm not sure what this fuzzy brown crab is but I don't trust crabs at all in aquarium so I would go ahead and try to capture it, than see if I can identify it.Little crabs don't stay little for very long unless they are commensal crabs associated with Acroporids.

The little fleas around your sand bed are probably some amphipods or copepods( small crustaceans). Harmless and part of detritivore crew in the tank.

Here's a good articles to read about small bugs in aquaria.
http://reefkeeping.com/issues/2002-10/rs/index.htm
http://reefkeeping.com/issues/2004-09/rs/index.htm