Thin white worm.

[lf11casey]

I saw a worm of some sort in my yoyo tank last night. It was about half an inch long, white and thin like a hair. I thought it was a cat hair, but it started to swim in an s like motion. I haven't seen it since so I can't get a pic, if I do I'll try to, although I'm not sure it will come out with my camera.
Any thoughts on what it could be, or is there a really good site some where with good photos so I try to identify it myself?
Thanks

[shari2]

Sounds like planaria.
http://freshaquarium.about.com/cs/qa/f/faq0050.htm

feed less, clean the substrate obsessively for the next several days and keep up with your vacuum maintenance.

They don't harm the fish, some will even eat them (like angelfish). They will rapidly proliferate in a gravel substrate that collects a lot of detritus. If your substrate is gravel and more than an inch deep you'll need to work hard at cleaning it out well. Do a section at a time, and make sure you cover the complete depth and surface.

[bslindgren]

If it was thin and round it would have been a nematode, or roundworm. The vast majority of these are beneficial or at least not detrimental, and very plentyful in the substrate and filter medium. The densities in organic substrate can be mind-blowing. Some are parasitic, but I wouldn't expect a parasite to be out swimming around - they live inside the fish and only infective eggs or young would be out. These would be too small to see. So my guess is that it is a fairly harmless guest you have.
Planaria are flatworms that move more like slugs on the substrate (although they can swim if dislodged, but then more like a ray), and to my knowledge, there aren't any white ones. They include the familiar Dugesia (which are brown or black), which has gained fame as a lab animal with incredible regenerative powers.
Since they do feed on organic waste, overfeeding may still be the root cause if you see a lot of them.

[shari2]

thanks, bsl. when I looked at close up pics of the planaria i couldn't imagine them being the little threadlike things i have seen in the past that casey was describing. but looking around, several places seemed to say planaria fit that description.

bah. the internet is only as good as the user...

[lf11casey]

I didn't think they were planaria, I have these in my shrimp tank. These worms are round, 1/2'', thin, and like I said white. So I guess like bslindgren said they're most likely a nematode or round worm.
I don't think I'm over feeding and I even skip days, and the loaches eat everything within 2 minutes most of the time, but I could be wrong. I'll be more careful.
I have a sand substrate so that is real easy to clean. I'll just keep an eye on it all and if I see any more worms I will try to get a pic.
Thanks.

[zmo63]

I have no idea, really, but this reminded me of this thread on the North American Native Fish Association forum about horsehair worms. Could that be it?

[bslindgren]

I have no idea, really, but this reminded me of this thread on the North American Native Fish Association forum about horsehair worms. Could that be it?

Horsehair worms are really long (5-6 inches) and black or brown - the adults literally look like horses' hairs! The adults are non-feeding, but most of the life-cycle is spend as parasites of crustaceans.

[wasserscheu]

Oligochaeta are common to not treated tanks. It’s a large group of worms, to which the earthworm counts as well. Amongst other features, they have short hair, which I think, nematodes don’t have. They are harmless, at least in my tank. I guess I got them in by feeding live tubifex only once. Have them for more than 4 years now. They provide a nice live food source for little fish.
They swim with head steady, the body moving in “sinus-movement”

Here some older pic’s of mine, that fit your description