Note :
The below is simply a basic description. If it receives enough interest or approval to move forward, I'll write it out in full depth as a proper creature, with emphasis on its uses and cultural impacts in the North Suvan, specifically Syliras, Alvadas, the Svefra in the area, and the Isurian craftsman in those two cities.
I want to greatly emphasize up front that the metallic bones would not be a new/superior metal to anything. With the high amount of impurities, it would often be a brittle metal, but due to its unique coloring, only used as adornment. Not for use as structural material.
Name: Syliran Shiner
Location: Coastal waters of Northern Suvan Sea
Frequency: Rare
Physical Appearance: A silvery rope fish, grows 2'-4' feet in length. Much heavier than it seems it should. Has a large sucker for its mouth.
Unique Traits: Metallic bones, often a blended alloy of the different types of metal it has consumed. This metal is often used in a decorative fashion, having different effects based on the different levels of metal in the alloy. Common traits include a kaleidoscopic color sheen, an adaptive color, to match the color of a majority metal it is worked onto, and anti-reflectiveness, to prevent it from shining when exposed to light. Shine Oil, the fish's oil, when cooked out of the meat, can be applied to metal for an everlasting shine and rust resistance. This oil is odorless, but can sometimes add a slight colored sheen to the metal it is applied to, often silvery blues, greens, golds, and purples.
Requirements to Catch: Competent+ Fishing, Competent+ Bodybuilding, Metallic Bait, Extra Strong Rod or Line
Extra Requirements: Novice+ Cooking to cook meat, Competent+ Cooking to obtain Shine Oil, Expert+ Metalsmithing to melt down the bones properly, Expert+ Blacksmithing or Weaponsmithing to work Shiner Metal into usable things
History/Cultural Impact: The Syliran Shiner has been a favorite fish of the Syliran community, first discovered stuck to the anchors of ships. Their decorative properties let craftsman make more unique pieces for customers. Isur were the first to discover how to work their metallic bones, using them for crests and jewelry on armor. Hunters, criminals, and others prefer the dull aspect to the metal, preventing their weapon or armor from shining when hidden.