Officials say fish in Regina's Wascana Creek are suffocating due to low levels of oxygen in the water.
On Monday, a large number of dead fish were discovered at the Albert Street bridge and others were moved to a better location.
Officials said crews from the provincial Water Security Agency successfully rescued an estimated 600 to 800 fish on Monday night, moving them from a spot near the bridge to Wascana Lake where oxygen levels are higher.
"There are a number of factors that contribute to low dissolved oxygen levels including lower water levels," officials from the city and the water agency said in a statement Tuesday. "Previous years have seen more precipitation resulting in higher water levels, faster flows in the summer and more oxygen and therefore more fish in the water."
They added that if any more dead fish are found, they will be removed by crews from the city.
"If dry weather continues, oxygen levels in the water will continue to deplete in the evening and could impact fish," the statement said.
Officials noted that releasing water from the lake into the creek would only lower the lake and cause problems for fish in the lake.
In April a number of dead fish were discovered on the shores of the lake following the spring melt of ice.
A spokesman for the Wascana Centre Authority told CBC that issues relating to oxygen levels in the water occur from time to time.
The authority added there have not been any known or reported spills, chemical dumps or harmful effluents entering the water, that could be linked to the dead fish.