During the 1996-1997 period, dynamics and structure of zooplankton and benthos in sugar mill canal in Crvenka (Serbia, Yugoslavia) were studied. Two representative sampling sites were chosen, while the third one served as a control site, providing it has no impact on cage culture. The canal section where the cages were established, had previously been drainage and dredged. Immediately after the refilling, the zooplankton qualitative structure was scarce, with dominating Rotatoria. Two months later, the situation improved and Cladocera and Copepoda emerged. Those two groups of organisms have the major role in enhancing the commercial feed consumption Soon after the refilling, the benthos was reestablished. Sample analysis shows the presence of Oligochaeta and Chironomidae. Qualitative and quantitative analysis of benthos points out no significant difference between the canal sections upstream and downstream the cage culture.

There are some water reservoirs on the territory of Zajecar district area (Serbia). Their purpose and time of building are very different. It is also different the organic matter production in those reservoirs. Water reservoirs for supplying with drinking water are very specific because the increased of organic products makes some difficulties in process of refinement reservoir water to drinking water. In this paper we are trying to explain, taking the reservoir Grliste for the example, if the biomanipulation exerts on water quality in the reservoirs.

Thermal waters represent an unused natural potential of Serbia. A possible way of utilizing this resource is to carry out the initiative that has been underway over the past several years to use certain thermal waters for the rearing of some allochthnous thermophilic fish species, the most famous among them being the group Tilapia (fam. Cichlidae), authochthonous in Africa and Asia. The analysis of basic physico-chemical properties of the Ovcar Banja (Ovcar Spa) thermal waters (the bed of the Zapadna Morava river, Western Serbia) indicates the possibility of their utilization for this purpose.