AN ECOLOGICAL STUDY OF FISHES AT A SITE IN UPPER AMAZONIAN ECUADOR

Resumen

This paper includes information on fishes collected at a site in the Upper Amazon basin (Santa Ce- cilia, Napo, Ecuador). Habitat and food preferences have been recorded in addition to climatic and limnological data that were compiled during six months of investigation. The area studied includes swamps, small creeks, a lake and moderately-large rivers of two drainages that join some 1088 kilometers east of Santa Cecelia. Twenty-one families of fishes (101 species) were recorded as follows: stingrays (1, 1); characoids (7, 58); gymnotoids (3, 3); catfishes (7, 30); cyprinodonts (1, 1); synbranchoids (1, 1); and cichlids (1, 7). Stomach analyses revealed the majority of fish to be in- sectivorous, the bulk of their food being terrestrial in origini. Stingrays, cichlids, gymnotoids, and the majority of chara- coids and catfishes fed largely on insect forms, ants being the most abundant single food item. Loricariid and buno- cephalid catfishes, and anostomid, prochilodontid and curi- matid characoids seem to feed principally on plant material and bottom organisms. Large characoids and cichlids were primarily piscivorous.