WATER QUALITY PARAMETERS WHICH INFLUENCE RAINBOW TROUT (Oncorhynchus mykiss) WELFARE IN CLASSIC SYSTEMS.

Water quality parameters determines the success or the failure of a fish culture operation, so any proper-prepared plan for aquaculture must describe the quality and quantity of water available for this purpose. The aim of this study was to evaluate the physical and chemical water parameters in Rainbow trout culture, in the summer season from three salmonid farms, due to the environmental changes that are nowadays happening and affect the fish culture operation. The water samples were collected from Bistria-Năsăud County, from three trout farms: Strâmba, oimul de Jos and Fiad, in the summer of 2018, between May and August. For the determination of water parameters (dissolved oxygen, total dissolved solids, electrical conductivity and resistivity, pH, temperature, salinity) was used the Hanna HI 9828/4- 01 Multi-Parameter and for the chemical parameters (total ammonia, nitrates, nitrites) samples were transferred to the USAMV laboratories. The samples collection was made in each farm from three different places: catchment, basins and evacuation water areas. The results of the study showed that the parameters observed from the three farms were different, with major differences in month of July and August. The environment of fish aquaculture is a complex system with critical parameters as are the temperature, suspended solids, dissolved oxygen, nitrite and ammonia. However, the temperature and the dissolved oxygen are the most important parameter, requiring continuous monitoring in aquaculture production systems, due to the fish aerobic metabolism which requires an elevated level of dissolved oxygen at optimum temperatures. [ABSTRACT FROM AUTHOR]