Is This A Flatworm?

Well, I feel that's a bit harsh... I've actually done quite a bit reading on the topic.

As I said, there are many points of view and opinions on the topic of bristle worms. I'd suggest you read the many posts available and form your own conclusions. As stated, they are a part of the clean up crew and consume detitrius in your tank as plus side. I have also read other points of view. I believe it is Six Line Wrasses that consider them food... so if you have a Six Line Wrasse, I wouldn't worry.

The beauty of this hobby is that there are many approaches and many ways to success.

M