Dory's character in "Finding Nemo" is a blue tang fish. Blue tang fish are characterized by their bright blue coloring and yellow tail. These fish are found in the Pacific and Indian Oceans.
In contrast to some other species of fish, blue tangs do not normally swim in schools and are more often found in pairs along the coral reefs. While these fish look harmless, they actually have a unique defense mechanism to ward off bigger predators. Each fish has spines along its back and tail that are venomous and unfold to inflict damage on the predator when the fish is caught.