Ecological aspects of the fish fauna of the Mucajaí River, in the Paredão Island region, Roraima, Brazil

Ichthyofauna survey were carried out in the Paredâo Island region of the Mucajaí River, where possibly, in the future, a hydroelectric dam will be built. A total of 126 fish species, belonging to 28 families were captured, at two collecting sites, one below and other above the Paredão 2 falls. Although these two stations were separated by a 20 meter waterfall, the similarity between the communities was high. Shannon's diversity index, evenness and catch per unit effort (CPUE) were rather high, comparing to other Amazonian rivers. The high value of equitability (0.82) suggests that fish communities are in equilibrium. In terms of biomass, the predator species were dominant and in number of specimens the detritivores were more abundant. It is expected that the construction of a dam would affect the equilibrium of the fish communities in this area, by lowering the number of fish species and changing the composition of the fish communities