A fish's time is running out. Pollution, overfishing, poaching, ecological incivism, climatic disturbances, acidification of water, fish stocks are decreasing. At this rate and if we do not change our comfortable habits, there will be no more fish in the seas and rivers in 2100. The most fragile are the smallest. A female cell meets a male cell to build a living being according to a genetic program specific to each species. We are no exception to the rule, neither fish, but in what natural environments now? The oceans are becoming acidic, warming, pollutants are more and more numerous with various polytoxicity. Nature is necrosis, it disturbs the course of life, the smooth running of births. A few minutes after fertilization in water, the membranes of fish eggs change. The egg hydrates, swells and then protects itself by hardening. Everything happens very quickly, you have to save at all costs the life that starts, which is very vulnerable in the first seconds of fertilization. The system is not yet in place, the cell is turned upside down by the newcomer: the sperm and the channels of exchange with the outside environment are still anarchic. This is the danger, because it is at this time that pollutants enter the egg to stay there and weaken embryonic development. The membrane of the egg hardens, selects certain contaminating molecules which still arrive during embryogenesis to cross the cellular barrier to impact the embryo. Side effects are unpredictable and can appear immediately and much later in different life stages of the fish.