Thermal and Oxygen Conditions in Carp Ponds During the Summer Period

The work presents changes of oxygen indices in carp ponds during the summer season. The basis of the research were regular water tests conducted in two ponds: Mydlniki II intended for carp farming in the second year of fish production cycle and Bocian used for carp farming in the third (final) year of breeding. The temperature of pond water in July and August was optimal for development and farming of cyprinid fish and ranged from 16.6 to 30.5 °C. The lowest value of oxygen dissolved in water (6.4 mg·dm sup>-3) was registered in Mydlniki II pond and was higher than the oxygen optimum for carp (5 mg·dm sup>-3). Oxygen saturation in water of fish ponds exceeded the optimum upper limit value (168%) on a few dates, however, it posed no lethal threat for fish. In August in Bocian pond oxygen saturation fell within the range of optimal values, creating better conditions for fish development. In the secondary pond (Mydlniki II) it was found that oxygen saturation in water on 12 dates was lower than the low optimal value (96%).