Dory, the small blue fish with a bad memory from the "Finding Nemo" franchise, is a blue tang, or a Paracanthurus hepatus in scientific terms. Blue tangs are native to the Indo-Pacific and found in coral reefs, and they weigh around one pound and are generally 10 to 12 inches long. While these fish are typically found in the ocean, they can also be purchased at pet stores such as PetCo. When in captivity, blue tangs can live up to 20 years. However, it is important to note that keeping a blue tang in a home aquarium can be challenging and requires careful consideration.