Tritonvt; The family analogy might work as long as there were no issues other than food intake. But, the more family members we add, the more waste there is to be dealt with. Now, that might not be a huge issue with indoor plumbing but fish have no convenient way to dispose of waste. They live with/in it. Thus the concept of biomass, oxygen availability, increased disease, etc. in a water hole.
Also, there ain't no free rides. Adding 2 more family members means the first 3 usually have to do without something, maybe space in the house or quality of food or some sacrifice to accomodate the 66% addition to the population. Of course, all of this assumes a stable income with no salary increase or no move to larger quarters.
