Fish leather is actually a thing you can make
Like every food industry, fishing has leftovers and the fish skin is part of what is left after the fish is gutted and cut for shipping. Most of the fish and its parts are used, except for the skin. Turning these into leather makes perfect sense.
Though not common and certainly new for most of the western world, using fish skins is a tradition in some parts of the world. Among first nation tribes it’s an old practice and the Hezhe tribe in north-east China is known for its fish skin dresses. Most fish leather is currently produced in Scandinavia, particularly in Norway, Iceland and the Faroe Islands.
Fish leather is considered to be very sustainable, as the process is fairly simple and effective. It is mostly used in the fashion industry, to produce garments and accessories and successfully turns a leftover into a valuable by-product. Moreover, it benefits remote communities up north.