At the present thesis they were employed with Lemna minor L. and Eichhornia crassipes M. water plants from July until October, 2014, cultivated in fish farms fluent in Moyobamba city, this study seeks to improve more the quality of the effluent one using the water plants, realizing a previous treatment before there being spilt to a body recipient (Gully), expiring with Maximum Permissible limits of water un load. A study was realizad using floating water plants (Lemna minor L. and Eichhornia crassipes M.) to remo ve biodegradable organic matter in effluents from fish farms taking a pilot plant with two systems of treatment: a system in batch es and a continuous system. The system in batches consisted in the application of Lemna minor L. and Eichhornia crassipes M. aquatic plants using the effluent from fish farms to analyze the purifying effect of the aquatic plants, taking a reactor of ...