Help Id on this invert, flatworm or leech?

[tsmith_old_guard]

I just planted this aquarium 2 weeks ago. I have a dozen Amano shrimp for algae control, no other fish or shrimp. This will be a neocaridina shrimp tank once its seasons. I got into the office early today, before the aquarium lights went on and I saw 3 of these guys swimming in the water column. Once the lights came on, they disappeared quickly. I was concerned that this flatworm of whatever type might be predatory toward shrimp the way leaches and planaria can be. I figure I need to medicate the tank. My LFS recommended Flatworm eXit by salifert. I have some. I wanted to see if anyone might help me identify it. Honestly, once my plants had filled in and I was done planting, I was going to nuke the tank with fenbendazole to make sure there were no hydra, planaria, snails, etc. before I introduced neocaridina shrimp. Thoughts, suggestions, treatments, etc.?

 

[Koan]

mosquito larvae!!

Bigger fish will eat them , but in the meantime I would net them out before they turn into fliers and come after you