Rowenna Uppstream moves from her secluded, Piscean community to the global terrestrial world and finds out the hard way that fish weren't meant to eat a carb-heavy diet.

WIP world-building background:

Fish are pretty much amphibious. They can breathe in water and on land, but they are mute by terrestrial standards. They talk, it’s just not in the same way as normal speech. They probably have TTS for living with other species. I haven’t world built that much, but I decided that fish mostly keep to their own communities and have a very reserved culture. They don’t practice excess or waste; they live in quiet moderation. But the rise of globalism has seen many moving to terrestrial communities for work or just to get out into the world, and the culture shock can be pretty severe.

Fish didn’t evolve to eat carbs and sugar (since real fish mostly eat algae, plankton, crustaceans/mollusks, and lean meats) so they are at risk of weight gain. It’s enough of a general problem that there are Piscean PSAs about the dangers of leaving home and how to live in a global society and live a healthy life… but we all know how effective those are in real life.