The article contains results of an investigation on contents of oxygen de-mand in fish ponds water fertilized with biologically treated municipal sewage. Additionally, during collection of water samples there were also analyzed water reaction and pond’s water temperature. Researches were carry on in vegetative season in 2006. The object of research was fish pods of Komorowice complex, which are located in North part of Bielsko-Biała. The chosen ponds: Green and Stone are characterized with individual inflow and outflow of water. The chose ponds are characterized with different technical parameters. Green pond is shallow one – its average depth is about 1 m, with area of 4,2 ha, which give water capacity of pond 42 000 m3. In turn Stone pond have smaller area – 3,3 ha, but is almost two times deeper then Green; its average depth is about 1,7 m which also give greater water capacity of pond: 59 200 m3. In paper were qualified changes of oxygen demand, temperature and water reaction in pond’s water. Additionally, were qualified basic statistical parameters of analyzed indi-cators: an average, minimum, maximum value, standard deviation and interval. Analyses made in ponds showed, that in 2006 vegetative season contents of oxygen demand ...