Worm id

[untamed]

That is absolutely a Eunicid worm of some type. I have at least 4 of that exact species in my tank and can confirm that that particular one can reach a length of 2 feet. ('cause one of mine is that long...in a hex tank that is only 13" per side)

I've had them for a more than a year and my conclusion is that they are fairly harmless scavengers that will eat whatever is available. I don't think they would hunt fish, but might take a bite out of soft corals. They will accept hand feeding and have a high "wow" factor with house guests.