Though the average specimen in captivity might live 25 or 35 years, an old koi named Hanako, from Mino province in Japan, has been shown to be over 215 years old based on analysis of her scales, and other 100+ year old fish are known from the same pond. Koi, like wild carp, can grow to 36 or more under perfect conditions.
The gold and silver medals weigh 412 grams (0.9 pounds) and the bronze medal weighs 357 grams (0.78 pounds). They are the biggest and heaviest summer Olympic medals ever made.
Had all 812 gold medals been made entirely out of gold, with the current market value, they would be valued at: 812 medals x 500g/medal x $42.4.g = $17,214,400. The last time an Olympic medal was made entirely out of gold was in 1912 at the Stockholm, Sweden summer Olympics. At the time, the average price for one ounce of gold was roughly $18.93 and the weight of the 1912 Stockholm Olympic gold medal was about 24g (0.77 ounces). The cost of a solid gold Olympic medal was approximately $14.58 in 1912. Even adjusting for inflation, it would cost far less than half the cost of the Rio Olympic gold medal.