Question: asked about remedie for oxygen depeltion in fish pond and cow dung application 
Answer: please dont apply cowdung or gobor 
lime 10 kg per bigha, mix with water, keep for 4 hours and apply
next day apply potassium permanganate @ 280 gram per bigha, mix with water
oxymore tablet @ 20 to 25 per bigha 
reduce feed for fish for 1 month
cowdung application when water colour is clear green or green