You have a freshwater pond in front of you and it is winter time. The Pond is NOT frozen over. You are trying to decide at what depth a goldfish should be swimming, in order to breathe at its maximum physiological benefit. There are no other variables to consider at all; other than the surface of the pond is located exactly at sea level.

there's the proffessional site that will you.

the answer is true when observing or determining population size, a direct observation is use, in which each organism is counted in a population or in an area. one benefit of this measure is that you get the exact population count but it will take a long time to  determine  the  size  of a  population.

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.