Feeding patterns in five predatory fishes of the high Paranà River floodplain (PR, Brazil)

Abstract

Abstract— Between March 1992 and February 1993 five piscivorous fish species, Acestrorhynchus lacustris (Reinhardt, 1874), Hoplias malabaricus (Bloch, 1794), Rhaphiodon vulpinus Agassiz, 1829, Salminus maxillosus, Valenciennes, 1840 and Plagioscion squamosissimus (Heckel, 1840), of the high Paranà River floodplain showed a wide total prey spectrum though only three to four taxa were dominant in their diet. Shrimp, Macrobrachium amazonicum, were also common to the majority of species. Seasonal and spatial variations occurred throughout the study period probably due the availability of prey species. The main resources shared by the predators were also the most abundant in the area, with consumption markedly focused on prey about 5.0 cm long. Detrended correspondence analysis was effective in discriminating two groups of predators species that exploited distinct microhabitats. The predators with the least scores consumed small characids that inhabit mid‐water or the littoral region, whereas those with the largest scores consumed prey associated to the bottom.

Feeding pattern of Salminus maxillosus (Pisces, Characidae) at Cachoeira das Emas, Mogi-Guaçu River (São Paulo State, Southeast Brazil)

“…Several studies show that bigger fishes may profitably take food from a wide range of sizes, as was the case in this study. This tendency was also observed by Almeida et al (1997) who reported that for the five piscivorous fishes studied in the Paraná River floodplain, small prey were preyed upon by all fish up to those of 45.0 cm in length. Loureiro & Hahn (1996) found that for Hoplias malabaricus bigger specimens tended to include smaller prey, suggesting that with growth a wider range of prey are captured.…”

“…Considering the food composition of S. maxillosus our results showed that this species was essentially piscivorous, consuming exclusively fishes of three species, but showing preference for Leporinus sp. Almeida et al (1997) found that this and other predatory species in floodplains of the Paraná River completed its diet with insects, crustaceans and some grasses, consuming 11 diferent fish species. The low diversity of food ingested by S. maxillosus in our study, probably reflects not only the environment, poor in macrophytes and associated insects as well as in fish species during most of the year, but also the fact that young specimens, that may consume insects (Morais Filho & Schubart, 1955) were not analised.…”

Dynamics of the feeding ecology of selected fish species from the Okavango River delta, Botswana

“…Therefore, this observation suggests the possible existence of food partitioning based on feeding time. A similar observation was made in the Amazon (de Almeida et al 1997) where niche differentiation among competitive species occurred through differences in feeding times, in habitat utilization, and by the ability of species like Rhaphiodon vulpinus Spix et Agassiz, 1829 (Characiformes) to have a greater "feeding flexibility". Diet similarity does not necessarily suggest direct competition for food, but rather that similar food resources are being used (Mathews et al 1992) which might of course result in direct competition when food becomes limited.…”

Morphological differentiation among migratory fish species from the Paraná River basin

“…The morphological patterns identified for the nine long-distance migratory fish species analyzed, which separated them into four distinct morphological groups, may indicate the existence of differences in the swimming capacity and modes of locomotion. Group I was formed exclusively by R. vulpinus, a piscivorous species living in the upper layers of the water column, migrator (Ferreira & Caramaschi 2005, Agostinho et al 2003, and its morphology is adapted to capture prey on the surface or medium depths (Almeida et al 1997). Therefore, R. vulpinus differentiated from other migratory species studied for its body shape, long and laterally compressed body as evidenced by fineness ratio (higher values).…”