To answer your question, no. They are two different species of fish.
Just to point out to you..
- A 5 gallon is too small for those fish.
- Those are both schooling fish, keeping one of each is a bad idea
- You should upgrade to a 20 gallon tank
- and get 4 more of each
It is possible your fish has bloat. In that case you can treat him, by first cooking a pea and peeling off the skin, than putting it into the tank. The pea should help with digestion. If that dosen't help with the bloat your going to need to do some research on bloat and find a good medication to treat it.
But again you should upgrade your tank to a 20, and get the correct number of fish to school.
Not only that but I implore you to do some research on fish before you buy them next time. And research the fish you have.
Good Luck :]