At present, aquatic expander has been popularized in the field of aquatic feed. As a green feed product with high feed intake rate, high conversion rate and more environmental protection requirements, expanded aquatic feed has been more and more accepted by the market. With the further improvement of expansion technology, many manufacturers have changed the original processing technology of hard granular aquatic feed broken by granulator to directly use extruder to produce small granular aquatic feed. The molds for producing small granular aquatic feed are generally 2.0mm, 1.5mm and 1.0mm, and even the particles required by some manufacturers are smaller, which is called "micro granular" expanded feed.