Fast swimming worm with red body/white head

[DiscoMush]

Last night I found this fast swimming worm in my tank. Does anyone know what it is? Thank!

 

[blaxsun]

Nothing good...

 

[Clarkjw2002]

Looks like some kind of oligochaete, or hirudinid (leech). What did the mouthparts look like? being a fast swimmer I'd suspect some kind of ectoparasite.

Not sure if something like prazipro would work for this type of worm. These treatments are meant for round/flatworms, not segmented worms.

 

[N.Sreefer]

@Jay Hemdal

Jay does this look like an ectoparasite to you? Ever see something like this attached to a fish?

 

[Jay Hemdal Verified Community Expert]

Last night I found this fast swimming worm in my tank. Does anyone know what it is? Thank!

Generally, fast moving organisms are not parasites. Some can be micro predators, but the worm parasites I know of are slow. I don’t know what this is though - seems to have a segmented body though, so not a fluke. I don’t see a sucker at both ends, so not a leech.
Kay

 

[michael_cb_125]

It is a species of ragworm or clam worm.
We see them at certain times of the year in massive swarms along our coast. The do not sting, but can bite.

 

[michael_cb_125]

Surf fisherman catch them and use them for bait to catch pompano, whiting, spots, etc.

I am pretty sure they are a predator of bivalves...

 

[Clarkjw2002]

Believe there is one family of Leech that has secondarily lost the suckers and parasitic lifestyle. If I remember right they are predators of snails or bivalves.

So might not be good but maybe not all that bad either—unless it’s eating all your snails or clams.

 

[DiscoMush]

Believe there is one family of Leech that has secondarily lost the suckers and parasitic lifestyle. If I remember right they are predators of snails or bivalves.

So might not be good but maybe not all that bad either—unless it’s eating all your snails or clams.

Interesting! I have a pretty good number of CUC members in my tank, but haven't seen any deaths - thankfully. I've taken it out since I'm worried it'll eat my corals/fish

 

[DiscoMush]

It is a species of ragworm or clam worm.
We see them at certain times of the year in massive swarms along our coast. The do not sting, but can bite.

Thank you! I've never seen anything quite like it and it hadn't come up on any hitchhiker ID guides I've used. I've discarded it as a precaution

 

[DiscoMush]

Generally, fast moving organisms are not parasites. Some can be micro predators, but the worm parasites I know of are slow. I don’t know what this is though - seems to have a segmented body though, so not a fluke. I don’t see a sucker at both ends, so not a leech.
Kay

Thank you! This is really reassuring.

 

[DiscoMush]

Looks like some kind of oligochaete, or hirudinid (leech). What did the mouthparts look like? being a fast swimmer I'd suspect some kind of ectoparasite.

Not sure if something like prazipro would work for this type of worm. These treatments are meant for round/flatworms, not segmented worms.

I didn't really get a good look at the mouthpart, but it didn't seem to have any pinchers/fangs

 

[michael_cb_125]

They don't appear to have biting jaws, but they do, lol. I have found out the hard way, haha