The characteristics describe organisms found in the domain

A. Archaea

Explanation:

Domain Archaea is the group of single celled prokaryotic organisms. These organisms lack a well defined nucleus and cell organelles. The cell wall of these organisms lack peptidoglycan which makes them distinct from bacteria. These organisms are tolerant to saline conditions and they survive in marshes, hence they are called as halophiles.  They produce methane as a metabolic byproduct, therefore are called as methanogens.    

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.