I don't like BiOrbs. They don't allow for the proper surface exchange of gasses and oxygen. Traditional rectangular tanks have a very good reason for being that shape, it wasn't just lack of imagination! You need as much surface area as possible for the built-up gasses in the water to dissipate, and for oxygen to enter the water.
These BiOrbs were created by someone who knew there were enough uninformed people out there that he could make a killing off of a tank shape that is really not a good design at all. It just looks neat. They're also outrageously expensive! Take the same amount of money, and you can buy an awesome, more traditional set-up.
Something else to think about. Any 16 gallon tank cannot house more than 16" of fish. That doesn't mean one 16" or even two 8" fish can live in it. Rather, it could house eight 2" fish. That is really limiting yourself. This tank is not nearly big enough for a Pleco, either.
If you are bent on this tank, you could try some Platies. They are pretty hardy and might survive. Guppies are another option. Get all one sex of either of these or you will soon be overwhelmed with fry.
Since you are a beginner, I urge you to go to a book store or library and get some beginner's books on aquarium keeping. There is a whole lot more to keeping fish than "just add water."
Aquarium keeping is a fun and relaxing hobby, if you put forth the effort to learn as much as possible before trying. Proper preparation will save the you the heartache of watching all your new fish die off because you made a crucial mistake.
Hope this helps. Good luck!