A two foot silver arowana is a baby, even in captivity a well cared for silver arowana should easily reach 30 to 36 inches in ten years. The smallest captive adult size for any species or arowana is 24", my jardini is getting on for 18 inches and is still less than 2 years old!! Arowana's eat a lot and grow FAST, unless you already have a 6x2x2 tank and can upgrade within 2 years to at least a tank with a wider front to back measurement then arowana's are not for you.