鱼类病虫同其它生物一样，具有防御外界不良环境的本能，对长期药物的袭击产生抗药反应，尤其是对同一种药物的反复使用，病虫的抗药能力增强更为明显。在防治鱼病时，轮换选用有效药物，是避免产生鱼类病虫抗药性的既简单而有效的方法。轮换用药是把不同成份、品种的药物交替 Like other living organisms, fish pests have the instinct of defending against the adverse external environment and are resistant to long-term drug attacks. In particular, the repeated use of the same drug causes more obvious resistance to pests and diseases. In the prevention and treatment of fish diseases, the rotation of the selection of effective drugs, is to avoid fish pest resistance is a simple and effective method. Rotational medicine is the different ingredients, varieties of drugs alternating