Rhabdocoela

[Axelrodi202]

I recently found some white flatworms in my tank. I initially panicked because I thought they were planaria (I've lost whole tanks of shrimp to planaria before). I was beating myself up for possibly underdosing anti-planaria drugs when quarantining a new batch of recently added plants.

 

But then I realized they asides from being flat and white they don't resemble the predatory planaria I've seen in the past. They are no longer than 2-3 mm. They curl up into a ball when disturbed, but instead of sinking end up carried by the water current. Though one end seems a bit larger than the other they don't have the triangle/diamond shaped head, or the obvious dark eyespots. They can move somewhat fast but generally move along pretty slowly. They mainly stick to the substrate, though I did initially notice them by seeing one on the lower glass. 

 

Further research makes me think they're Rhabdocoela worms. Does this description fit the bill?

 

This tank was previously successfully treated for planaria with drugs, and all new plants since then have been quarantined with drugs as well. Do anti-planaria drugs not affect these?

Most importantly, do these affect shrimp in any way? I'm fine with leaving them in (I always like microfaunal diversity) if they won't decimate my colony.