My former GT would have clear poop once every 3-4 days, but then again he was the 3rd man on the totem pole of 3. So stress did play a part. I didn't see it coming out of him, it was just there when I cleaned the tank. However, a majority of the time (90%) the poop was colored. Sometimes the end of the poop did have a clear part.
If I recall correctly, his poop reminded me of pleco poo, much longer than a omnivorous/piscivorous type like oscar, bass, or pikes. I changed his diet to NLS Algaemax (more plant based) and I saw less of the clear lining as the months went on. They have a wafer version. I would recommend that over Hikari tropical wafers and see if that helps.
If you want to get a better look at the poop, slowly remove the substrate over the course of a week to see what is at the bottom of the tank.