Would be easier to identify if pic was taken soon as piranha was caught. I'm not definitely sure but I'm going with serrasalmus compressus.S. compressus
Serrasalmus manuelli, the colours are probably washed out
Thanks everyone for the help. I have one more Serrasalmus from that day if I can trouble you for another. I’m looking at S. maculatus for this guy. View attachment 1550967