I strongly suggest you read some fish books - you'll learn a lot of neat stuff.
RBP's grow to about 8 inches on average, but I have seen plenty of 10 inchers. A 75 gallon tank is probably suitable for 2 or 3. Needless to say, your 10 gallon, once again, will not house one of these fish.
Moreover, they grow very fast, so you could not even keep a baby in a 10 gallon for very long. (2 months or so.)
See my previous comments for alternatives.