How Old Is My Fish? Here’s How You Know

Have you ever caught a big fish or even a small fish and wondered how old it was? This is an important question for people who manage fish populations as they need to balance the water body with fish that are different ages. The Division of Wildlife Resources handles fish populations in Utah’s reservoirs and lakes. They have a post that discusses how the age of a fish is determined and it’s pretty interesting. 

Fish are kind of like trees. Just like a tree has growth rings that you can count to determine their age, a fish has growth segments on the scales that work in the same way. During the summer, the scales grow quickly and in the winter the growth is tighter. This leaves bands that you can count and figure out the age of your water dweller. 

This is a little harder than just pulling up the scale and peering at it. A biologist will use a microscope and solution to get the age. A second biologist will look at the same sample and then compare their results. This is a detailed analysis and probably not something you could accomplish on the shore with a fish squirming on a hook. 

Finding out the age of a fish is important for the management of fish populations in Utah and it's pretty cool that they can figure it out. If you don’t have the time and a microscope, you can find out how fast the species of fish grows and then get a good guess by its length. But if you are going to give it a cake with the proper number of candles, you will need a microscope.