South American Arowana
The Silver Arowana is not a fish that is suitable for beginners. Due to its large size and long life expectancy, only more experienced aquarists should undertake this challenge. It requires an enormous tank (at least 250 gallons in capacity for an adult fsh) and finding suitable tank mates for them can be challenging. They are considered to be carnivores and eat large quantities of food so this should also be considered before purchasing them, though you could make your own fish food to save money.
In terms of price, the Silver Arowana is normally the cheapest type of Arowana available. If you are looking to get an Arowana, try to buy them when they are at least 6-8 inches long. By this time they have started to mature and are much hardier which means you will have a better chance of successfully keeping them
Arowanas are not suitable fish for beginners in general. The Asian Arowana is smaller than the South American ones, and much more colorful and expensive.