I wonder if you just need a thicker skin?

I do think people who work in retail do make a difference. Maybe not same difference as a doctor. But sometimes a job is just a job. Paycheck. I worked in retail and waited tables and clean houses on the side or full time a lot. Who cares if customer is rude. It’s not like they are my family. They are strangers

I still work one night a week at the store. Kind of a habit I guess. Doesn’t bother me. I don’t care what customers think about me. I wonder why you care what they think about you?

PS I’d not tell them that fish is over fed (why is it over fed? Whoever is in charge doesn’t do their job right, it’s kind of neglectful). If they want to know something about fish and you aren’t in charge of them, tell them you’ll call a manager. Let managers deal with this.