Fresh specimens of A. arius were collected from Fort
Cochin, a high saline area and Arookutty, a low saline area,
during pre-monsoon (January to May), monsoon (June to
August) and post-monsoon (September to December)
seasons during the period of 1 year from January 2002 to
December 2002. Specimens of A. arius which included both
the sexes were collected and only the individuals which
belonged to the size groups between 100 mm and 270 mm
were pooled (total 178 numbers). Total length of all fishes
was measured. Salinity of the area was noted during the
collection. The gut analyses were made according to Hynes
(1950). For feeding intensity, the distention of stomach was
judged visually and classified as ‘gorged (overfed), full
(active), ¾ full (active), ½ full (moderate), with trace (poor)
and empty as described by Pillai (1952). The index of preponderance was calculated by the method of Natarajan and Jhingran (1961). The food contents were identified at
group level and the gastro-somatic index (GSI) was
calculated using the formula