Dried and frozen fish skin are two distinct raw materials, not different grades of the same product and the right one depends on what you're processing it into.

Frozen tilapia, barramundi skin keeps its natural moisture and protein structure intact which is why it's the form most collagen and gelatin manufacturers ask for: drying can promote protein aggregation that reduces how well skin swells and extracts during gelatin production, so processors chasing extraction quality tend to specify fresh frozen material. Exotic leather tanneries have a similar preference, tanning traditionally runs on green, frozen or wet salted hides because fully dried skin turns stiff and is hard to rehydrate without damaging the fiber structure a clean tannage depends on.

Dried fish skin trades some of that freshness for shelf stability: it holds at room temperature, ships lighter with no cold chain and stores for months rather than days. That's why pet food and treat manufacturers and snack/chip processors whose own processing (baking, frying, extruding) already reshapes the material prefer it: their priority is microbial stability and consistent moisture, not preserving native collagen structure.