Questions provide little information. Is it normal grass carp? If so, you can feed grass carp at a very low feeding rate, for example, the maximum daily feeding rate of grass carp fed with granular feed above 4 kg is only 0.9%, and stopping feeding every 7 days 1 day will not affect growth and yield; Switch to high-quality, low-fat, low-protein and brand-name feed to ensure that the feed does not contain growth hormone; Give fish plenty of water every day, and only feed 1 ton every day, which often makes them hungry and lean grass carp. It is estimated that the treatment will have an effect in more than 40 days. For reference only.