I entertained myself over a few pottery sessions making mechanical fish of this sort. They were loosely based on deep sea angler fish and maybe a bit of stingray to give the tail. All fins and teeth were made from oven setting modelling plastic clay stuff of the sort that kids use, while the fin webs were scrap leather. This is a more robust material than clay and so well suited to teh more vulnerable parts.

The glaze is simply an iron oxide wash that has been buffed back from the high points to let the terracotta of the clay show through.