What type

Hi again,as I am new to the forum, i am also new to the whole piranha buying thing.
I think with a little gentle persuasion, my parents will be willing for me to get a piranha. However, I'll have to do alot of research into the idea first. Which is where you guys come in...
I know I would definitely make a good owner,i already have alot of animals. But I dont know where to start when it comes to getting a fish of this type.
I've had a look arond at lots of pictures on here and at the different types. You all have some very beautiful and interesting looking fish. I dont want a big piranha (I know they can get to 60cm)
What is the smallest piranha you can get? and what is the smallest size tank you can keep them in? do they need feeding red meat everyday? or does each type of piranha get fed differently?
I'd be grateful for your answers and suggestions. Thanx so much :biggrin: