North Carolina Aquariums explains that fish survive in the ocean by using defenses such as camouflage, electric shock, chemicals and venom. Camouflage helps fish blend in with their environments to avoid detection. Some fish stun their predators by sending electric shocks through the water. Many species use chemicals to warn other fish when they feel threatened. Poisonous chemicals can be emitted from a fish's spines, teeth or barbs.
According to North Carolina Aquariums, countershading is a type of camouflage that describes a fish that has a dark back and a white stomach. When these fish are seen from above, their dark backs help them blend in with the ocean floor, while their white stomachs allow them to blend in with the sky.
Cryptic coloration is a method that fish use to change their color to match their environment. Some fish have patterns that break up the outline of their bodies to make them harder to see. Vertical bands occur on the skins of fish that live in the stems of aquatic plant beds.
Schooling fish confuse predators, because they usually have lateral bands that make the fish blend together. Young fish have an eye-like black dot on the base of their tails to trick predators. When the predator aims for the black dot, the fish has a better chance of escaping.