Sorry pal but Glass cats in a 5, no way, a 20 gal atleast, but on the bright side there are many other types of easy to find Nano fish that can do great in a 5gal, Chili rasboras and Bettas are ecspecially good in smaller tanks. Having kept 5 gallons i can say youd be amazed with all the different possibilities of things you can do with it, ive done Shrimp, CPD's, Bettas (only 1), Pygmy Corys, Guppies, etc...
If you really want to keep the glass cats i do advise a tank upgrade, a 20 or larger will suffice