Flatworms?!

[Zoolife xD]

hey guys i have a few questions on flatworms but first let me add some background information, i currently have a nano aquarium set up for a G. chiragra mantis shrimp and i has some other cuc in there as well but no corals or fish just a marine planted tank if you will dominated by macro algae. When i added the last round of macro to my tank i accidentally introduced what i believe to be flatworms. They are small only reaching about a 16th to an 8th of an inch in length total too small to really get a clear picture with my phone, and when small they are a light cream to tan and as they grow they take on the bright green coloration of the feather caulerpa in the tank. I have been keeping there numbers down by manually removing them during water changes, but haven't tried anything else.
So my questions are as follows...
1) Are these little critters indeed flatworms?
2) If so do they pose a threat to anything in my tank such as my mantis shrimp(I've heard some eat corals but again i have no coral i just haven't heard if they can harm anything else)
3) Should i remove them all together?
4) If so what is the most effective manner in which to do so that is safe for my mantis shrimp?

 

[nautical_nathaniel]

Without a picture of them we aren't going to be 100% sure they are flatworms but based on your description they probably are flatworms. Besides overpopulating and looking ugly, they probably aren't going to do anything too bad unless they take to eating macroalgae. I can't imagine they would harm the mantis in any way either. I would continue manually removing them as needed, otherwise the mantis shrimp may start to eat them. I wouldn't try to dose anything to kill them since it will likely also affect the mantis and other CuC members.

 

[saltyfilmfolks]

See if it matches any of these.

https://www.lionfishlair.com/hitchhikers-guide/

 

[Zoolife xD]

Without a picture of them we aren't going to be 100% sure they are flatworms but based on your description they probably are flatworms. Besides overpopulating and looking ugly, they probably aren't going to do anything too bad unless they take to eating macroalgae. I can't imagine they would harm the mantis in any way either. I would continue manually removing them as needed, otherwise the mantis shrimp may start to eat them. I wouldn't try to dose anything to kill them since it will likely also affect the mantis and other CuC members.

Thank you very much, i figured that their turning the same color as the macro was probably attributed to them consuming it as their main food source but I wasn't 100 percent sure so I figured I'd ask. And one more question, are there any cuc members known to consume flatwoms?

 

[Zoolife xD]

Looks a lot like the brown flatworms acoel variety, thanks for the link @saltyfilmfolks

 

[nautical_nathaniel]

Thank you very much, i figured that their turning the same color as the macro was probably attributed to them consuming it as their main food source but I wasn't 100 percent sure so I figured I'd ask. And one more question, are there any cuc members known to consume flatwoms?

It's either that or they have an adaptation that allows them to change color based on their surroundings, probably the latter though based on my understanding of flatworms haha However, they could also be eating commensual/parasitic algae on the outside of the macroalgae, so keep a close watch on things.

I had a red Hawaiian reef lobster that ate all of my flatworms, asterina stars, hitchiker brittlestars, and most of my sand-sifting starfish but I doubt he would get along with the mantis in any way.

 

[Zoolife xD]

It's either that or they have an adaptation that allows them to change color based on their surroundings, probably the latter though based on my understanding of flatworms haha However, they could also be eating commensual/parasitic algae on the outside of the macroalgae, so keep a close watch on things.

I had a red Hawaiian reef lobster that ate all of my flatworms, asterina stars, hitchiker brittlestars, and most of my sand-sifting starfish but I doubt he would get along with the mantis in any way.

Yeah he would end up as fodder, I was hoping for some sacrificial snails of some sort but such is life lol, thanks for all the info and the quick reply.