In some species at a certain size, males of similar length
were heavier than females. N. australis and N. erebi are
an example of this in which the length weight curves
crossed at 60 mm and 280 mm respectively, suggesting
that males became larger than females at a given length
in older fish; the curves for N. australis were significantly
different. Three species (G. rostratus, M. p. peelii, and T.
tinca) indicated that the curve for males was marginally
steeper than females. The curves for M. adspersa and P.
grandiceps showed a markedly steeper curve for large males
than in females: and this was significantly different in the
case of M. mogurnda. This occurs because of the large
hump which develops on the forehead of the former and
the large broad head which develops in the latter.