The influence of the trout aquaculture in floating cages upon the chemical characteristics of the actual sediments in the farms neighboring area is reduced by a series of factors which cause that just a part of the organic and mineral matter introduced in the ecosystem to arrive on the bottom, under the cages. The trout aquaculture in floating cages influences the structure of the benthic macroinvertebrates’ communities by simplifying it, increasing the abundance and the weight of the detritivorous oligochets. These effects appear on limited areas in the farms neighboring area and may be explained as forms of a limited eutrophication.