Fish markets sell food grade produce, Fresh or frozen.
Bait and tackle shops and servos don't sell food grade product.
You can buy them fresh at the markets and salt them, but you pay more.
Pilchards have a soft flesh, and if they go thru frozen thaw, frozen thaw, they become mush.
From the tackle shop In small bag portions the fish should all be separate. It's harder to judge blocks.
I buy frozen and salt them.
Always WA Pilchards, avoid Australian Pilchard labels, they are crappy herring.