In ponds with greatest stock density high values of oxygen consumption causing decreases in O2 concentration were noted. The use of aerators eliminated oxygen stratification. High values of phosphate content were observed. In ponds with silver carp polyculture the oxygen conditions were more beneficial and the content of N-NH4 was smaller than in ponds with an additional stock of grass carp. In all the types of ponds PO4 concentration suggested accumulation of this compound.