Our data showed that, though the predators preferred the gold fish, they did not completely disappear from the population. They were, however, reduced from the first generation. New fish are born every year, and among the new fish are gold ones that may be added, and then eaten by the sharks. There was a significant reduction from the first generation (6 gold, 4 brown) to the fifth (three gold, seven brown). From now on, only 30% or less of the population may be gold fish because of the birth and death rates.
Our findings also relate to the Hardy-Weinberg equilibrium. First, there was no mutation. The fish did not change at all during this experiment. For example, the fish did not randomly become white cheddar instead of the regular goldfish. They stayed the same at all times. Second, the breeding population of fish is quite large. The "ocean" is filled with hundreds of fish, ensuring that the gold fish do not completely disappear. Third, the population of fish is isolated from other populations, and no differential migration occurs. There are no other varieties of fish present. For example, pizza fish can not join the population of gold and brown fish. Fourth, all members of the population can survive and reproduce, because there is no natural selection. All of the fish have equal ability to reproduce, because there are no other variations between them, so they all have equal ability to survive as well. Finally, mating is random. We added this fish by closing our eyes and randomly selecting three fish from the "ocean". There was no artificial selection involved in mating.