Scientists have discovered that fish can become depressed and may be the key to developing antidepressants. According to the Department of Biological and Environmental Sciences of Troy University in Alabama the neurochemistry between fish and humans is very similar. Fish are tested in what is called a “novel tank test’. A Zebrafish is dropped into the tank. If it sinks to the bottom it is a sign of depression as opposed to if it swims to the top and begins to explore. Severity is measured by how much time it spends in either location. It is by these observations that the researchers have determined that this is a form of depression. If depressed a fish usually loses interest in both food and exploration. Given a mild antidepressant the fish will eventually swim to the top of the tank a sign that it has overcome the depression. Not only do fish show the capability of using tools but they are also able to recognize faces. If a tank has an adequate amount of space and vegetation a fish will explore and be in constant motion, a sign that a fish is happy in its environment.