it depends what kind of piranhas you get. Sorry, I must have skipped the questions. There are Red Bellies for sale at my pet store for $6. I dont think they're any harder to care for than ordinary fish. You put them in a tank big enough for them, make sure the water temp stays between 74-78 F, make sure the pH is neutral, and add feeder fish. That's really all there is to it. I don't need a license in my state, but you should check that out before you buy them. I added some links in another post that I wrote earlier. These places will ship to your door. The cheapest piranha I bought was $9, the most expensive one was $40. The price varies, but Red Bellies are probably going to be cheapest. The red belly that is in my gallery I have had for just about a year now, and when I got him he was an inch long. The red bellies grow pretty fast. I have him in a 55 gallon tank, and if I wanted to I could add a few more in there with him. They don't need a super large tank, but don' t crowd them in either. If you have any more questions you can ask away.