Some species has less bones, like catfish or trout.

And you use to heda to maek fisherman's soup. This needs a base, cooked from the heda and fins, then the bits are ground essentially, separating everything that's inedible, then some real slices of the fish is cooked with the base. The base is often cooked from carp or a bunch tiny fishes, and the slices are catfish for example.