I use anchovy fillets in alot of recipes to add umami and nutrients, not just sauces but also things like meatloaf. Fishiness dissipates pretty quickly with heat, even faster with acidic ingredients like tomatoes, citrus, or vinegar. It's pretty easy to modulate fishiness, even with just acid. I double or triple the anchovies in a typical caesar dressing recipe, and if I feel I over did it just adding more lemon juice tamps it down.
One of my kids is pretty picky, even sensitive to onions, but doesn't seem to pick up on the anchovies. She'll eat fish, though, depending on mood, so maybe she's not the best benchmark.
I use massive amounts of anchovies in my cooking and various types of processed fish generally. They do not trigger the extremely strong “rancid fish” effect of e.g. Vietnamese fish sauce that some people can taste even in small quantities.
The anchovies disappear into the food. For people like me, the fish sauce never does, you just get a mouthful of rancid fish taste. People gave up trying to hide it from me years ago because nothing really seems to work.
That's the spirit! But you shouldn't underestimate the power of suggestion:
"This was cooked with fish sauce" -> "This tastes fishy"