In my experience cheaper grass fed beef in the US commonly tastes gamey which can be interpreted as fishy.

More expensive grass fed doesn't have this problem, so it likely has to do with diet or the cut.

The difference could also be due to how long the beef is hung or aged. Beef tasting too “gamey” might not be hung long enough (suggestion made last night by small farmer friends, fwiw).

i guess it depends on what type of fish you eat. I often eat relatively fresh salmon. I wouldn't say it tastes fishy even though its fish. It tasty oily, so much oil comes out in the baking process.