Question: asking  about oxygen deficiency in fish farm pond
Answer: first put 10 bundle of dry paddy straw on the surface of the pond water and change or wash this paddy straw after 15 days and put again please follow this step for 1 month
apply lime @ 10 kg per bigha for 1 month mixing with suitable amount of water and keep it for 1 night and broadcast it over the pond water 
reduce the number of fish in th farm pond as the recommended for traditional method is 800 to 1000 for 1 bigtha pond 
after 5 days of application of lime apply oxymore 20 tablet per bigha 
and continuously agitate the pond water surface by using a bamboo