GloFish Tetra white / translucent strand coming off of it.

Hello! I picked up this Tetra 7 days ago and it hasn't been eating, has been breathing heavily, and hasn't been really active compared to my other tetras. All my other tetras are fine but it's this one Tetra that is having issues ever since I got it. Attached are some photos of some things I've noticed with this Tetra over this past week. What is going on with this fish? My water parameters are fine. I'm currently in between constipation, an internal bacterial infection, internal worms, or some type of parasite.