Addition of vegetable protein: physical substances such as cottonseed meal, rapeseed meal, sunflower meal, peanut meal, corn germ meal, pea meal, rice husk powder, wheat bran, straw meal, rice bran meal, sawdust, instant noodle waste, etc.
Addition of animal protein: hydrolyzed feather powder, shrimp powder, vulcanized feather powder, intestinal feather powder, leather powder, wool powder, blood powder, meat and bone powder, meat powder, squid powder, etc.
Fish meal adulteration: This is the most advanced adulteration method compared with the above. Fish meal mixed in this way is also difficult to identify. Among them, there are domestic and miscellaneous fish meal mixed in Peruvian fish meal, sold as Peruvian fish meal; there are also Vietnamese fish meal mixed in domestic fish meal, when domestic fish meal sold.