Fish Tank
To see or clean a fish tank in your dream, indicates how you have full control of your emotions. You keep your feelings in check. If you are watching the fish in the fish tank, then you may feel that your life is going nowhere or that you are going in circles with your life.
Fish
To see fish swimming in your dream, signifies insights from your unconscious mind. Thus to catch a fish, represents insights which have been brought to the surface. Alternatively, a fish swimming in your dream may symbolize conception. Some women dream of swimming fish when they get pregnant. The fish is also an ancient symbol of Christianity and Christian beliefs. Consider the common phrases "like a cold fish", "fish out of water" or something that is "fishy" about a situation. It may also imply a slippery or elusive situation. Perhaps your dream could be telling you that "there are plenty of other fish in the sea", with regards to some relationship issue.
To see a dead fish, signifies disappointment and loss of power/wealth.
Aquarium
To see an aquarium in your dream, signifies that you have acknowledged your emotions but have not yet confronted them. Thus, it may refer to your unconscious thoughts or repressed sexual desires. Also, you may feel that your life is going nowhere or that you feel it is going in circles. Alternatively, the aquarium may indicate that you need to calm down and set some time for yourself to relax and unwind.