Sorry for the loss. It looks like an adult male Metynnis altidorsalis.
The cause of dead is unlikely to be age. I have a trio of Metynnis maculatus (two males, one female) who are a documented 26 years of age. In the same tank, there is an adult Metynnis altidorsalis which has been with me for 6 years and it was an adult when it arrived. Plus 1 female altidorsalis, and a pair of spotted (M. lippincotiamus), that makes seven dollars in a 125g. 5 paleatus cories and 2 Brochis, and a few Otto’s complete the stock in a well planted tank. No problems with the plants, as I have shown before.