I found it. Here's how.

1. Copy the save file to a new location and open it using wordpad (or other).

2. Scroll to the end to find the long lists of fish names

3. Move the cursor to before each fish name and hit enter. Be sure to scroll to the right to make sure you get each fish name on its own line.

4. The fish names that have yyyy (with dots above them) seem to be the fish you have not found yet.

Note: After breeding the fish, I did have to close the game, then re-copy the save file before the yyyy went away.