How to determine the age of a fish?

 How to determine the age of a fish?

      Theage of a fish can not be estimated with great precision at a glance, even if its size gives some indication. Several methods are used:

      The analysis of the scales:                           

      It is a question of taking some scales of a fish, to treat  them  to make  them readable. Clear areas correspond to summer periods where the fish eat  a  lot and grow faster; dark areas, to winter periods where they feed little then their growth is slow this method is called scalimetry.

      The analysis of otoliths, operculas and vertebrae:

      In case the scales  are  illegible. This  second  method  is  then  used  to  observe  the areas on the otoliths, calcareous concretions of  the inner ear. It allows to determine the age of the fish, but also to know to which species they belong.