Newbie Questions

I'm new to saltwater so bear with me. I've seen some kind of worm in my 30 gal tank. It's at least 3in long and it retracts really fast into the rock. What is that? Do I get rid of it? If so, how?

Most worms are harmless and are beneficial to the tank as they eat all the detritus in your sand bed. If it has spines, then it is most likely a bristle worm.
Some varieties of bristle worms can eat your corals, so if you see your corals being damaged, check them out with a flashlight at night to see if it?s the worm that?s doing the damage. The greater majority of bristle worms are harmless to your tank, however they can sting you, so be careful when moving rocks and corals around.

They sell 'bristle worm traps' (I?ve seen them at petCo) which is basically a long plastic tube with a tapered hole on the end, that you put some bait in. The worm goes down the hole and cant figure his way back out. Others have made traps using any kind of small container with holes and bait. I?ve heard of people using a leg stocking with bait in it.

There are also fish that will eat bristle worms. However, the same fish usually will eat other similar critters in your tank such as other good worms, feather dusters, and copepods. One good fish for eating bristle worms is the six line wrasse.

Check out Ron Shimek's links here:
http://www.rshimek.com/reef/OnlineArticles.htm
Scroll down to the sections on "Annelida" and "Polychaeta (Bristle Worms)". The links there should help you identify your worm and decide what to do about it.

Grenadino,

Welcome to SW

Dallas - good advice - and you'll vind mostly good advice from this board -

Additionally, if the worm is in your rock and is extending 3" chances are it is not a harmful worm - I have worms like that in my tank and some of them look just like earthworms - any chance we can get a picture ? or are they usually only visible in the night?

House

On other thing to mention, if it is a bristle worm, and it most likely is, you should be careful when handling the sand or rock in the tank. Bristle worms are covered with tiny fibers that can easily get stuck in your hand when you move things around. They are nearly impossible to see and are extremely painful and irritating.

If you've ever had a piece of fiberglass stuck in your hand, it's about the same.

Thanks a lot guys for the replies. It does have a color like an earthworm. I don't have and corals yet but so I'm not worried about it eating anything. I aslo have the light out so I can control green alge. I comes out ever so often cause the tank is situated in my office so it gets light from the surroundings.

It's most likely peanut worms. As Dallas said, most worms are harmless.

Over time, you'll be amazed by the diversity of life you'll find in your live rock and sand bed.