the frog might end up killing the trigger or vice versa, too small, your plannign too upgrade right? If your not sell the trigger to the lfs, i think you can keep a frog in a 25. what species is the frog?
If you get the frogfish, be sure to let us know how it goes. When i went to the beach a couple years ago i would always catch them when i went fishing. I wanted to bring one back with me and keep it but the LFS guy talked me out of it, saying that they make bad pets and no one keeps them. They are cool looking though. Good luck.