The length – weight relationship and relative condition factor of the shovel nose catfish, Arius subrostratus (Valenciennes,
1840) from Champakkara backwater were studied by examination of 392 specimens collected during June to September
2008. These fishes ranged from 6 to 29 cm in total length and 5.6 to 218 g in weight. The relation between the total length and
weight of Arius subrostratus is described as Log W = -1.530+2.6224 log L for males, Log W = - 2.131 + 3.0914 log L for
females and Log W = - 1.742 + 2.8067 log L for sexes combined. The mean relative condition factor (Kn) values ranged from
0.75 to 1.07 for males, 0.944 to 1.407 for females and 0.96 to 1.196 for combined sexes. The length-weight relationship and
relative condition factor showed that the well-being of A. subrostratus is good. The morphometric measurements of various
body parts and meristic counts were recorded. The morphometric measurements were found to be non-linear and there is no
significant difference observed between the two sexes. From the present investigation, the fin formula can be written as
D: I, 7; P: I, 12; A: 17 – 20; C: 26 – 32. There is no change in meristic counts with the increase in body length.