Indeed it is the total length.

The relation between the total fish length and their weight is represented by the relation ::

tW = a tL b where

tW = total weight of fish in g; tL = total length of fish in cm; a and b are

characteristics of environment and species.

By logarithmic transformation, we obtain a linear type relation:

log tW = log a + b log tL

This transformation makes it possible to reduce the variability and to homogenize the two variables (tW and tL).

The coefficient b (slope of the regression line) varies between 2 and 4, but it is often close to 3. It expresses the relative shape of fish body. When it is equal to 3, growth is called isometric. When it moves away from it, or at least is different from 3, the growth is allometric. A coefficient b greater than 3 indicates better growth in weight than length and vice versa (Micha, 1973, Ricker, 1980).

Indeed it is the total length.

The relation between the total fish length and their weight is represented by the relation ::

tW = a tL b where

tW = total weight of fish in g; tL = total length of fish in cm; a and b are

characteristics of environment and species.

By logarithmic transformation, we obtain a linear type relation:

log tW = log a + b log tL

This transformation makes it possible to reduce the variability and to homogenize the two variables (tW and tL).

The coefficient b (slope of the regression line) varies between 2 and 4, but it is often close to 3. It expresses the relative shape of fish body. When it is equal to 3, growth is called isometric. When it moves away from it, or at least is different from 3, the growth is allometric. A coefficient b greater than 3 indicates better growth in weight than length and vice versa (Micha, 1973, Ricker, 1980).

It should be total length for the calculation of lenth-weight and length-length relationship for obtaining 'b' values or 'k' values.

Thank you Oum Kalthoum Ben Hassine and Rakesh Prasad Bhagat ! Good to have clarification!