Polycheate ID? bristleworms or something else?

RabidDragon · Sep 30, 2022

These worms come out every time I do a water change. They showed up a couple months ago and have been increasing in numbers. They are growing larger, currently about 1/4 of an inch and swim in the open water like a corkscrew. I'm sure they are spawning when they are doing this. I've caught a number of them and they suddenly release a large number of eggs on the slide... I'm going to have a lot more of these things very soon. good clean up crew? or harbingers of doom? wrasses eat them? Mandarins?

Thanks for your help, see pictures and videos below. (ignore incorrect time stamps, these were taken tonight, 9/30/2022)

background surface is a non-stick frying pan.

Before laying eggs:

starting to lay eggs:

after laying eggs, note you can view the peristalsis action within.

Wasabiroot · Sep 30, 2022

My gut is saying an epitoke (reproductive and swimming optimized life stage of Annelids ) but I'm not sure what genus or family. Maybe Nereididae? Someone who knows invert taxonomy/biology can hopefully chime in. It would explain the spiraling swimming at least.
Not 100 percent sure though...