Dreaming about killing fish symbolizes the need to assert dominance or control in certain aspects of your life. It signifies feelings of aggression, power, and the desire to overcome obstacles or challenges. This dream may reflect a need to take charge of a situation or conquer personal insecurities. Alternatively, it could indicate repressed anger or the urge to eliminate negative influences from your life. Consider the context and emotions experienced during the dream for a more accurate interpretation.