Is there a change that some food got stuck somewhere?
I said worm cause It's happened to me before after I left a piece a food stuck under driftwood.
It's might be something else, lets see if other members has other ideal/vision
Yer cool, Iam not new to keeping fish I have 8 tanks in my fishroom, I hope it's not what you said or it means I have not been looking after one of my tanks correctly, and keeping my tanks in mint condition is something I always try to do,,
Just looking at those pics it look like planaria which is usually caused from overfeeding, but since you say you dont overfeed, im a bit clueless what else they could be???