Diet of Iheringichthys labrosus (Pimelodidae, Siluriformes) in the Itaipu Reservoir, Parana River, Brazil-Paraguay

Iheringichthys labrosus is a secondary commercial fish species in the Itaip u Reservoir, but it is important in other reservoirs of the basin. However, little information exists about this species in the literature. The purpos e of this study was to describe the diet of this species in the Itaipu Rese rvoir. Stomachs of 306 fishes were analyzed, collected from October 1994 to September 1996 in the differents zones of the reservoir (according to a lo ngitudinal gradient). The reservoir was separated into riverine (upper reac h), transitional (middle reach), and lacustrine (next to the dam) zones. Ma in items in the diet of 1. labrosus were aquatic insects (mainly Chironomid ae) and mollusks (mainly Bivalvia). Their presence in the diet did not vary according to zones. Also, there was little seasonal variation in the diet. This indicated a conservative diet that could be a result of the high abun dance of the items in the reservoir, or restrictions imposed by its buccal and digestive apparatus.