Of course you can, if you refer to:
- A scientist, who studies fish (ichthyologists), for example, often refer to different species as fishes.
- To the Bible, as Jesus fed thousands of people with loaves and fishes.
- The movie The Godfather popularized the saying that someone sleeps with the fishes to indicate that he or she has been killed by the mob and dumped in the water.
- A few different sayings that begin with If wishes were fishes.