In the rainy season every year when the weather remains overcast and the sun rarely shines, dissolved oxygen in fish farms decreases to a lethal level which may cause mass scale fish mortality leading to huge financial losses due to collapse of the fish crop. Director General, Fisheries Punjab Dr Muhammad Ayub told APP here on Sunday that in such circumstances, fish farmers are advised to reduce manuring and feeding to half, especially during the peak rainy season, and to maintain water level up to five feet at least, according to a press release. Frequent bobbing to the water surface for breathing by the fish indicates acute low concentration of dissolved oxygen (DO), which problem can be overcome by introducing fresh water, producing waves through twirling of a rope on the water surface etc. These measures can help save the fish life and prevent monetary losses to the fish farmers. He said that entire field staff has been directed to conduct periodical visit to all fish farms and guide the farmers for taking timely preventive measures. Dr Ayub said that in case of any difficulty, farmers can see district officer Fishereis, Divisional Deputy Director or Director concerned for more information and assistance.