Is it a bristleworm?

[Reefing_addiction]

Saw this swimming in my tank and quickly grabbed a net and put it in a container? Question is what is it?

 

[Spieg]

Looks like it.

 

[Reefing_addiction]

Bump

should I put it back?

 

[Reefing_addiction]

I’ve heard good things and bad so I don’t know what to do..lol

 

[Spieg]

They don't usually cause problems in tank (they're actually pretty good for CUC). Be careful with bare hands in tank though... those spines sting if they stick you.

 

[firechild]

It certainly looks like a bristleworm (polychaete). These creatures are much maligned in the hobby but the reality is there are thousands of species of polychaetes, of which, few are harmful. Most are scavengers and will generally not feed on the live things in your tank that you don't want them to.