Scientists identify the age of a fish by what is on the fish?

In general, the identification of the age of the fish are mostly used to observe the fish scales on the "annual rings", fish scales are with the growth of the fish body and the growth of a circle, so it will leave like the tree's annual rings like the lines, which in the lower water temperature in September - March, the fish body grows slower, the "annual rings" will be narrower, while after March until mid-August, the water temperature is higher, metabolism and growth rate is fast, resulting in the "annual rings" will be narrower. Wheel" will be narrower, and after March until mid-August, the water temperature is higher, metabolism and growth rate is fast, resulting in a "wheel" is wider, so after zooming in to observe, a narrow and a wide is an age, less than an age to record an age. I hope it can help you