I believe most 150s are also 6'. Mine is at least. They are also only 18" deep though. Even though arowana are flexible, 18" isn't a lot of room for a 30-36" fish to turnfrnchjeep;4423771; said:It will take years, but a black aro will hit 3 feet. A 300 is a good footprint for one, but bigger is always better (thats what you tell the wife, too).
I think a 150 is only a 4 foot tank, so not enough room for an aro to swim. A 125 is 6 feet, but is only 18 inches front to back, so not enough turning room.