The
concern in mitigating the negative impact generated by the discharge of
nutrients in the receiving water body is a challenge for the sustainable
development of Brazilian fish farms. Thus, the purpose of this study was to
evaluate the water quality and environmental impact caused by trout farming
system effluent with focus on discharge of phosphorus. Sampling was performed
on a weekly basis in triplicate from September to November 2010. Sample sites
were distributed according to the water flow: upstream from trout farming
system, water supply, effluent, artificial wetland, mixing zone and downstream (60
m from effluent). In the field, pH, conductivity, dissolved oxygen, water temperature
and turbidity were measured. In laboratory, nitrogen and phosphorus series, chlorophyll a, total solids suspended and their organic and inorganic fractions were
analyzed. For the good growth of trout in production system, the abiotic
factors described in the water quality monitoring demonstrated acceptable
values. Environmentally, after passing through the production system and
artificial wetland, there was an increase in concentrations of total phosphorus,
total nitrogen, orthophosphate, ammonium, chlorophyll a, total solids suspended and their organic and inorganic fractions
(P < 0.05). These results are related with the quality of feed, feeding management
and the inefficiency of the artificial wetland. Therefore, it is necessary to
use best quality feed to meet the nutritional requirements of trout, maintaining
an optimal feed conversion and reducing pollution generated by effluent.