Evil worm?? Help!

[jennytheleopardgrouper]

I just bought several fish yesterday and threw them in my main tank (yes..I know...my bad) Well this morning I found this....THING swimming around, eating alongside the fish. It swam just like a fish and thats what I thought it was for a second. It's about an inch long, a little longer. It's slightly greenish at the front, and a more yellow-brown towards the end. My questions are: 1.What IS this?
2.Is it bad?
3.Would it have come with the new fish...inside one I guess since I checked each before putting it in the tank...
4.I just fed Cyclopeeze for the first time. Could the worm have been in my tank all along and just came out of hiding seeking a new treat?

Thanks!
Pics are at
http://jagraphoto.com/gallery/v/jennyp/misc/worm1.jpg.html
and
http://jagraphoto.com/gallery/main.php?g2_view=core%3AShowItem&g2_itemId=1352

[Willow]

looks like some kind of bristle worm, i suspect it came out of your live rock or sandbed. opinions are mixed on good or bad, it wont harm your fish i dont think, may munch on corals when bigger, eats detritus mostly.

[jennytheleopardgrouper]

Do Bristleworms swim like that though? It seriously swam like a fish...I'm worried it may be a leech of some sort...one that travels in packs...

[marie]

I believe it is an epitoke,the sexually reproductive stage of some types of bristleworms. Some info here http://www.reefs.org/library/aquarium_net/0697/0697_2.html

No more harmful then any other worm :biggrin: