Hi...
the significance depends on the exact manifestation of your thoughts in the dream, so it's difficult to say without knowing more about the dream in depth.
Generally, though, fish symbolism is usually connected with sexuality (the mermaid with her tail rather than usual female organs), or on the other hand, can be a phallic symbol (the shape of the fish).
In some cultures fish dreams are connected with money...I am not sure why (perhaps because of the simple reason that it is profitable to sell fish for eating or decorative purposes as a garden ornament, such as koi carp).
It's difficult to say without knowing more of your dream and whether it seemed a pleasant dream at the time or not. I hope it turns out to be a pleasant one for you.