Scientists can tell how old a fish is by reading the growth rings on the fish scales, a lot like they do with tree rings. 

Fish have a specialized sense organ called the lateral line which works much like radar and helps them navigate in dark or murky water.

February 24, 2012 | Categories: From the Gremlin

Fish have a specialized sense organ called the lateral line which works much like radar and helps them navigate in dark or murky water.