The most likely explanation for the variation is the offspring were produced from different combination of genes. A single pair of gold fish mentioned in the question means a male and a female gold fish. The two of them mated and contributed different genes to the fertilized fish eggs, this results in production of various body shape and colouration which is known as variation.
65.Food Shelter and Protection
66. a particular section, group, or type of people or animals living in an area or country.
67. a community of animals, plants, or humans among whose members interbreeding occurs.
68. Rainfall is a limiting factor because not alot of areas get water around here.
69. Individual, Species, Organism
Population
Community
Ecosystem
Biome
Biosphere
