a pic of the spot would be helpful.. my puffers got tiny little air bubbles stuck to their tummies before but it never looked like something was coming out.. sounds like a worm or parasite but i could in NO WAY be sure
i did want to tell you that those puffers are EXTREMLY sensitive!! i lost 2 before i got my little Buck Nutty .. they get deathly stressed out soo easily & need perfect water conditions / temperature to thrive.
some might say different, but IMO
you have to take extra EXTRA care of a puffer to ensure they have a healthy life.
but w/ all their personality, its worth every minute of it!!