What are the methods of measuring growth rates of fish?

Question

What are the methods of measuring growth rates of fish?

Answer 1

It depends on the scale of time you're examining.  You can get a pretty good estimate of growth rate over longer periods of time using otolith ring widths.  Otoliths are commonly used to age fish because rings are laid down similar to tree rings, but some studies have found that they can be used to determine growth rates as well.  However, you have to kill the fish to get to the otoliths.

If you are keeping live fish, then the easiest way is to weigh and measure them every day.