To see fish in a dream symbolizes insights from the subconscious or it could mean conception since many pregnant women see fish during unconscious dreams. Fish are sources of nourishment and symbolize food for the psyche. Fish also stand for Christianity and Christians as these creatures represent Jesus Christ.
Fish in water portrays an overwhelming emotion, according to DreamMoods.com. To decipher what the dream means, consider the state of the water in which the fish swims. Cleaning a fish in a dream illustrates altering of emotional expressions as it relates to other people; a dead fish represents loss of power or wealth.
According to About.com, dreaming activates the limbic system of the brain responsible for emotions, memories and sensations. The amygdala and hippocampus combine to create images in the brain as neurons and synapses attempt to interpret these electrical signals. Dreams occur during rapid eye movement (REM) sleep and activate the motor part of the brain even though the body doesn't move as much when humans sleep.
Psychologists going back to Sigmund Freud believe dreams illustrate subconscious desires. Contemporary scientists theorize dreams clean out psychological clutter of the past few days. In order for the brain to store information better, dreams offer visual stimuli that file memories away for later recall. About.com states that dreams can make the mind refreshed for the next day, almost like defragmenting a computer's hard drive to make the device more efficient.