This picture is of a group of fish known as Danios. These fish belong to a group called R-strategists and they practice R-selection. R-selection is the idea that the main goal of a population or species is to reproduce as much as they can. Danios lay on average 100-150 eggs at a time and the eggs hatch after 2 days. Danios, like other R-strategists create a lot of offspring with very little effort. In fact, it takes so little effort for the Danios to make offspring and lay eggs that the Danio fish are infamous for eating their eggs. The idea behind R-selection is that r-strategists are often the prey, so they need to reproduce quickly and as much as they can before they get eaten. Also, the ability to reproduce so quickly and effortlessly, resulting in many generations very quickly, allows an r-strategist species to evolve quicker.