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 no where 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.
Alligator:
To see an alligator in your dream, symbolizes treachery, deceit, and hidden instincts. It may be a signal for you to take a new perspective on a situation. It may also represent your ability to move between the material world of waking life and the emotional, repressed world of the unconscious. Alternatively, the alligator represents healing powers and qualities. An alligator also suggests that you are thick-skinned or insensitive.
To dream that you are running away from the alligator, indicates that you are unwilling to confront some painful and disturbing aspect of your unconscious. There is some potentially destructive emotion that you are refusing to acknowledge and owning up to.
Cobra:
To see a cobra in your dream, represents creation, and creative energies. Some situation or relationship has you hypnotized.
Piranha:
To see piranhas in your dream, suggests that something is eating away at your unconscious. You need to release some of those pent up feelings and confront those issues that are causing much internal conflict.
Running:
To dream that you are running away from someone, indicates an issue that you are trying to avoid. You are not taking or accepting responsibility for your actions. In particular, if you are running from an attacker or any danger, then it suggests that you are not facing and confronting your fears.
Chase:
To dream that you are being chased, signifies that you are avoiding a situation that you do not think is conquerable. It is often a metaphor for some form of insecurity. In particular, to dream that you are chased by an animal, represents your own unexpressed and unacknowledged anger which is being projected onto that animal. Alternatively, you may be running away from a primal urge or fear.
Swimming:
To dream that you are swimming, suggests that you are exploring aspects of your unconscious mind and emotions. The dream may be a sign that you are seeking some sort of emotional support. It is a common dream image for people going through therapy.
To dream that you are swimming underwater, suggests that you are completely submerged in your own feelings. You are forcing yourself to deal with your emotional difficulties.
you can also look for the other details in your dream, like "blue" or "green."