silver arrowanas are fairly common to st. louis pet shops.They grow fairly quick and get quite long.a small one will soon need a very long ,wide tank to swim,turn around.I have a 200 gallon Oceanic saltwater set up know,but i have had tropical fish all my life.feel free to ask for advise.I agree with the smelly comment on pirhanas,they require a lot of tank maintenance.If you don't mind investing some major cash,saltwater is the way to go.