Salt dissolves in water…
If anything, they’d drink it.
And what would be the point? They aren’t built for eating it (unless you’re talking about saltwater pufferfish, but even then their natural diet doesn’t include eating salt anyway). Frankly, most puffers are such picky eaters that you’d be lucky to get them eating frozen food before you even consider feeding them rocks.
Most animals really shouldn’t be given extra salt. Any required salt comes from their normal diet and any excess can be deadly.
You’ve posted similar questions many times with little information to go off of, so it’s hard to help without knowing any of the details. So short answer: no, you should not be giving any of your fish salt to eat.