Pacu Eye?

Hello! I am a sculptor working on a project in which I hope to be making a to-scale glass representation of a Pacu eye- I believe Tambaqui, the species found in the New York aquarium. I cannot find any resources to tell me how big their eyes are so as to order the correctly sized glass eye blank. Does anyone have any recommendations on where to look?

I am also a beginner, and if anyone has any suggestions on what materials to use/how to get started with painting this particular eye I would be very grateful! I am aware of the beginner's forum on this site, but if anyone has any other resources that would be of particular help for this one specific project please let me know. Thank you in advance!