So these pics are taken as of now, they have not been fed today, they were fed yesterday and not day before. Do I need to worry?
My "normal" puffer

The fat or air trapped or obese puff?



Water parameters all as expected (ammonia 0, nitrites 0, nitrates now 20 after new test kit).
2 schoutedenis, 4 starlight plecs and couple of male guppies.
Change 50% water weekly. Dose daily carbon and weekly ferts. Feeding variety of usual foods for puffs and at least 1 starve day a week though upping this to 2 per week.
Tank been up since Nov 2017, fishless cycled in the end after false start.