Hi, Mary,
I added the comparison period noted at the upper portion of the assessment in the FMV reasoning paragraph template I use for explanation.

Bony fish fossil , Possible Vinctifer Comptoni
Age: Possible Cretaceous or Eocene
Origin: Unknown
Measurements: 15.75" Length
Weight: not given

A beautiful fish with fine preservation of scales, fins and head details. From images, it appears that some mineralization has created a glimmer along the scales of the example. The specimen is an external mold of one flank of the fish, preserved in a calcareous concretion (possible limestone). The fish is likely a member of the Diplomystus or Knightia genus, a common yet scientifically significant representative of ancient aquatic ecosystems. The fossil is in good condition with minimal restoration. From images it appears that the matrix is stable with minor natural fractures, and no significant repairs are noted.

Recent auction results for comparable bony fish fossils from the Eocene Period indicate strong demand. The market for well-preserved vertebrate fossils remains robust, driven by interest from both scientific institutions and private collectors. To maximize the value, I recommend providing detailed documentation of provenance and authenticity. I also suggest a professional cleaning or stabilization, to enhance visual appeal.