Knives, in their first form, were little more than sharp shards of stone. Near the time of Pompeii and ancient Rome, metal knives began to supplant knives made of other materials. This is due to the advancements in smelting iron. In ancient Rome, purpose-designed knives were made. The fillet knife, with its long, flexible and sharp blade, is intended to fillet fish. This article describes where to buy a fillet fish.