Can you identify this?

[marcogig]

Hi all,
I have a lot of these in my Nano.
What is it?

 

[AydenLincoln]

That looks like a flatworm. Unsure of the species as some are bad. @vetteguy53081 Maybe you know?

 

[vetteguy53081]

Hi all,
I have a lot of these in my Nano.
What is it?

This is a planaria flatworm and while they are not harmful as red planaria, they in numbers can smother bases of coral and block the needed light for production of zooxanthellae which is their energy source.
Removal can be accomplished by siphoning them with a 3/8" tubing into a nylon stocking and discard
OR
Add a wrasse such as Yellow coris, 6 line, lunare or malanurus OR even a springieri damsel which will eat them

With the number you have, for the next 2 weeks you will have to look for eggs and scrape off as there is likely some and would be future acoels. Eggs are really tiny