Tell us about the arowanaâaka the dragon fishâand why it has become so valuable. The Asian arowana is the worldâs most expensive aquarium fish. It is a tropical freshwater fish from Southeast Asia that grows three feet long in the wild. Thatâs roughly the size of a snowshoe. [Laughs.] It is a fierce predator dating back to the age of the dinosaurs.
A personality disorder is an enduring pattern of inner experience and behavior that deviates markedly from the expectations of the individual's culture, is pervasive and inflexible, has an onset in adolescence or early adulthood, is stable over time and leads to distress or impairment.
Parkinson's disease (PD) is a degenerative disorder of the central nervous system that belongs to a group of conditions called movement disorders. It is both chronic, meaning it persists over a long period of time, and progressive, meaning its symptoms grow worse over time.arkinson's disease occurs when nerve cells, or neurons, in the brain die or become impaired. Although many brain areas are affected, the most common symptoms result from the loss of neurons in an area near the base of the brain called the substantia nigra.