Saowapa Angsupanich, Suthin Somsak, and Jutahthip Phrommoon

pp. 391 - 402

Abstract

The catfishes, Osteogeneiosus militaris and Arius maculatus, were collected from Songkhla Lake,
southern Thailand at two sites that varied in the extent to which they were exposed to higher salinity (the
Outer Songkhla Lake) and which were exposed to lower salinity (the Inner Songkhla Lake). Both fish species
were carnivores feeding mainly on benthic invertebrates with regard to its major components of Tanaidacea,
Amphipoda, Bivalvia, Polychaeta and Isopoda. Tanaidacean (Apseudes sapensis) clearly dominated the
diets of O. militaris in both sites ranging from 33.3 to 96.7% by frequency of occurrence and 23.5 to 90.2% by
number. Amphipods were the most dominant prey of A. maculatus ranging from 40.0 to 93.3% by frequency
of occurrence and 7.0-60.2% by number. Although Polychaeta were less numerically abundantly eaten by
catfishes (0.4-6.4%), the frequency of occurrence was high (10.0-86.7%) in almost all seasons. Some other
large (Alpheidae and fish larvae) and fast mobile animals (Mysidacea) were much more commonly found
in A. maculatus than in O. militaris. This study implies that these catfish species feed opportunistically on a
variety of prey in their environment coupled with preferential feeding.