White poop?

I have a narrow lined puffer who has been with me for two months in my 125.

He eats well, still hides under an over hang a bit but is kinda social. His favorite food is scallops. This morning I noticed that he had a long white poop following him. I have read that this can be a sign of parasites but am not sure since he seems happy, and is eating well. Not sure what to do.
Does anyone have any experience in this?