Fish comes to us from seas, rivers and lakes. Certain fish is cultured alongside rivers. Large-scale fish culture or fish farming is practiced all over the world. Table fish that is tasty is cultured, harvested and consumed. Those who do fish farming are called fish farmers.
Fish farmers dig large ponds and grow fish hatchlings which are fed with varieties of food. When fish grow to full size, they are caught and marketed.
One of the food items used in fish culture, is cocoon.
For centuries, fish farmers of south and central China have been growing mulberry trees on the embankments of fish ponds by the side of Yangtzee and Pearl rivers. Silk worms feed on mulberry leaves. Therefore, culture of silk worms or sericulture is also simultaneously practiced. This is integrated farming, where fish culture and sericulture are combined.
Silk culture produces a variety of food and fertilizer which are used in fish culture.
In silk culture, the excreta of silk worms are collected. When the silk worms become pupa, they shed skins. This is called slough. This is also collected. The pupal case or cocoon is made of silk. After the silk is removed, the dead pupas are collected. Thus, excreta, slough and pupa are obtained in huge quantities. This material is used as fertilizer and food in fish culture.
Fertilizer is essential for growth of minute plant and animal organisms in fish ponds. The fish, feed on these organisms, during early stages of growth.
Cocoon food, namely pupa, is obtained in bulks in sericulture. Cocoons contain more than 75 percent of pupa by weight. Pupa is rich in protein and fat. It is fed to the fish. It is estimated that the fish yield is twice the weight of the cocoon food.
Cocoon food is a natural byproduct of sericulture. It is cheap, and serves as rich feed for the fish.