Ew.... yes, that is unfathomably rude!!! In fact, I would order said person to go buy a can of febreeze and use the whole thing de-fish the work area! My ex-coworker used to microwave broccoli in the break room all the time, and everyone at work would tell him to stop, it made the whole store smell like shiyyyit.
I used to get into fights with my ex-roommate, because she KNOWS the smell of fish nauseates me, and yet she would eat tuna like eryday. Not only that, but she'd leave the can sitting on the counter and the juice in the sink - if she didn't DRINK THE JUICE from the can!!! Seeing her do this literally made me vom. :,( I could smell the tuna stench for days, as she never cleaned up after it or rinsed out the can. Thankfully I'll never have to see that tuna-loving b again.
I'm nauseous now...
<3 Erica, Gonzo & Fozzie