Need help ID.

[mowgli.reef]

So I was just checking my tank while the lights are off and found these critters. Need help IDing.

They look like flatworms but fast and hides when light is on them.

 

[nautical_nathaniel]

They look like flatworms to me too. See if you can get a good still image of them for a more positive ID.

 

[mowgli.reef]

Found one in the glass.

 

[Gumbies R Us]

@ISpeakForTheSeas

 

[EnterName]

Most likely a Ghost Flatworm. Here is a juvenile up close from my microscopy thread. The shape and color can differ slightly as there appear to be multiple species or strains in reef tanks:

See section 3 "Ghost Flatworm" in the Common Hitchhiker Guide.

They are harmless, but annoying. If you start to see the first ones now, it doesn't take too long until they are everywhere.