Help! Something is eating my Acros!

[sil40sx]

My first guess would be RTN from the tank being too young.

I had similar problem last year when I started my tank, I added a green slimer just 3 months after I cycled my tank, then viola, just two weeks in the tank, it started RTN.

 

[Lionfish Lair]

Thanks Lionfish Lair!
I've been looking for a good picture reference but haven't found one yet.

Sorry, I missed where you said this. The reason I guessed planarian, was because of a couple of things I saw in the picture..... the possible pharynx and the photoreceptors. This is definitely just a guess though. It's nothing I would worry about.

http://thenode.biologists.com/a-day-in-the-life-of-a-planarian-lab/lablife/