Análise físico-química e microbiológica da água em viveiros de peixes submetidos a diferentes dietas

Abstract

Fish farming is an agricultural activity that uses water resources for its development, whose main objective is to obtain a maximum production for human consumption, but without compromising the quality of the fish. Water is an important factor in fish farming, and quality changes are reflected in their physical, chemical and biological characteristics. The physico-chemical variants most used in monitoring water aquaculture activities are temperature, pH, electrical conductivity, transparency, dissolved oxygen, phosphorus and nitrogen. The microbiological quality of fish is influenced by the microbiological quality of the ambient water, and that the presence of fecal coliform in pollution indicators can change the quality of the final product. So the present study aimed analyze the monthly physical and chemical characteristics as temperature, electrical conductivity, pH, transparency, dissolved oxygen, phosphorus (in the forms of orthophosphate, total phosphorus and dissolved total phosphorus), nitrogen (in dissolved forms - ammonia and nitrate and Total - Total nitrogen) and microbiological water fish culture ponds under different feeding treatments with pelleted feed and extruded feed. Aimed at detecting which of the treatments were maintaining good quality cultivation of water. The nurseries are located in four rural properties in the town of Laranjeiras do Sul, Paraná. The water temperature, pH, conductivity and dissolved oxygen were measured, with the aid of a multiparameter probes. The water clarity was measured using the Secchi disk. Samples of pond water were obtained and placed in polyethylene bottles for analysis of abiotic variables. For microbiological analysis (total and fecal coliforms), we used the methodology of multiple tubes, which is the presumptive test, followed by confirmatory tests, in the following days. The bottles were stored in coolers for transport to the Microscopy Laboratory 2 UTFPR-DV, where the analyzes were processed on the same day of collection. From the results obtained it was found that the extruded ration due to their mode of processing is better assimilated by the fish, since this treatment was an observed reduction of nutrients in the water in the course of months. There was also reduction of aerobic microorganisms, unlike nurseries which were submitted to pelleted diet. In conclusion, the ration of extruded type enabled a better physical-chemical and microbiological quality of water in nurseries undergoing diet.