How structural adaptions support the theory of evolution by natural selection ?

natural selection is based on structural changes

Explanation:

Natural selection was proposed by Charles Darwin, who saw the changes of animals for how they were before through fossils, and how they are now, comparing their physical characteristics, among them, the structural adaptations of animals.

answer: 20 percent

the fish culture has become a developing commercial practice in developing countries which is already prominent in developed countries of the world. the major fish protein demand is being supplemented in developing countries is   fishing to meet the needs of the growing population. therefore, in some developing nations, the percentage of animal protein from fish in the diet can be as high as 20 percent.