What are these?

[KimS]

I just set up a brand new 60 gallon this week. I took a HOB filter from my established 72 gallon and all tests ran good so I added 5 neon tetras. The fish are fine but I've spotted numerous small worm like things swimming around. They are way too tiny to photograph. They are white, as thin as hair, and maybe half an inch long.

Any idea what they are and how they got into the tank already?

 

[HUKIT]

I'm sure they are Planaria which is nothing to worry about and easily fixed.

Aquarium FD - Planaria Small Hair like White Worms - Disease Identification, Diagnosis & Treatment

 

[KimS]

Thank you for the reply. I suspected planaria but didn't think a one week old tank could develop them that quickly. Do you think they hitched a ride from the pet store?

 

[BigJim]

They may also be nematodes. Nematodes look like shot white pieces of hair that squirm around in the water. They're harmless and free fish food.