This is a strange worm...

[CrocoDillon]

I found him swimming in my tank, never saw him before... he showed up swimming around... now I might never see him again.

Makes me wonder what creatures are in the LR that we will never know they are there.

Anyway, here's a pic (attached). I hope and think you can ID this one. Thnx in advance Dr Ron! (and other helpful posters)

[ofblong]

its a bristleworm. I dont think that one is bad but I had one that looked like that cept it was red that ate my mushrooms.

[CrocoDillon]

I've seen bristleworms, this one sure looks and swims different...

He only moves the things on his side to swim, not his entire body. He also seems to have a obvious different tail and body (seen on pic at about 1/3 from his head). He swims very fast in an almost straight line, unlike bristleworms.

[rshimek]

Hi,

Well, it is a bristleworm. The name "bristleworm" is useless as there around 10,000 species that fall into that category, so the name lacks any degree of precision. The behavior you describe is characteristic of a spawning worm, and they show up in many tanks from time to time.

Called "swarmers" or "epitokes" these worms are "budded" off of a parent worm (which remains in hole or burrow) and then swim away to spawn or distribute gametes (eggs or sperm).

Several groups of worms have this behavior, and without a better image (showing the head in good detail and crisp focus) or a specimen, I won't be able to identify it for you.

As with most of the worms in our tanks, though, it will likely be harmless or beneficial.

:D

[CrocoDillon]

Thnx, I might be never able to catch (or see) him again... but if I can, I'll try to get a better image.