Aiming4 Goldfish Care

I just got a new book to care for my goldfish, and it states that my Orandas may be at least three to four years old based on their caps, but that they only live 5-10 years. I was under the impression that if I give them a big enough tank and take care of [...]

Do I just put some in the water? How much do I put in? It’s a 20 gallon tank.
OK. I already have an air stone.
Miffy R is this what you were talking about:
http://www.amazon.com/Fish-Cycline-Tetracycline-250-Caps/dp/B0002YF9U0
?