What could be a proper noun for fish?

* Nemo, the clownfish from the movie *Finding Nemo*

* Guppy, the name of a popular freshwater fish

* Betta, the name of a popular freshwater fish

* Molly, the name of a popular freshwater fish

* Swordfish, the name of a saltwater fish

* Tuna, the name of a saltwater fish

* Salmon, the name of a freshwater and saltwater fish

* Trout, the name of a freshwater fish

* Walleye, the name of a freshwater fish

* Sunfish, the name of a freshwater fish