I only have a 5 gallon tank with one little goldie in it...can i have a live plant as well?

Of course! Be warned though, your goldie might make a snack out of the plant

What's the best type of plant for an oranda?

You're probably going to want to upgrade to a 10 gallon tank soon as fancy varieties (such as orandas) need 10 gallons EACH.

Pretty much any plant, but some plants get bigger than others.



-calico

It all depends on what type, and how much light you have on the tank. The wattage requirement for most live aquatic plants is 2-4 watts per gallon. If the lighting on your tank provides this much light, there's no reason you can't try growing live aquatic plants.