Nematodes? Detritus worms?

[JackBinimbul]

Hey, everyone! I've got some guests in my cycling tank that I'm curious about. I know why I have them, I know how to get rid of them and I know they are likely harmless, but I was wondering if I could get a positive ID. I'm thinking Oligochaete worms, possibly Chaetochaster diastrophus?

They are hair-like, only a couple of mm in length and translucent. I can't decide if they are blueish or that's just how they are reflecting my light. They have fine, bilateral cilia or spines. They move along the glass like a classic earth worm would, but I also see them floating in the water column. They don't "swim", per say, but they will undulate wildly sometimes.

They don't have eye spots or enlarged heads like planaria and appear to be segmented. This is the best shot I could get of a few near the seal.

This is a shot of the species I suspect:

 

[Autumnsky]

Had to look that one up. Personally not seen these in my tank. Didn't like the idea of 'paratomical fission' that creeped me out big time!!!

What do you want to/plan to do with them, if anything?

 

[JackBinimbul]

For now I'm just letting them enjoy their merry little lives. If it is oligochaete worms, they are related to earth worms and harmless. They are just eating up the junk in my tank. I did see one land on and then burrow into my filter sponge which was . . . interesting. They are the most interested in the piece of mopani that is growing fungus and algae. Which is interesting since the other piece still looks perfectly sterile.

When I get fish in there, they will likely eat them so, hey, free protein.