Although new here, I must disagree with the previous post. My family has owned silver arowanas since the late 70's (aka: since I can remember) and never in a tank larger than 150 gallons.
Our arowanas were always healthy and lived LONG lives. My brother, in his 150 gallon, raised an arowana that he eventually had to part ways with as he was moving. He sold it to a LFS and the owner stated it was the biggest, most colorful silver arowana he ever saw (and this LFS is the best LFS I've ever seen). This fish was measured at 34" from behind the glass.
I will concur that tankmates for an arowana are scarce and not recommended for a tank of the sizes you suggested.
Arowanas can be calm and peaceful... some are psychotic killers. It depends on the individual. My brother's large arowana above, was raised on pellet food, crickets... occassionally eating feeder goldfish. However, there was ONE goldfish his arowana did not eat... ever. It was a black/brown feeder put into the arowana's tank when it was about 1.5" long. Well, while all other goldfish had long since been eaten, this goldfish lived... and lived... and lived. Eventually, the goldfish grew to about 8-9" long. Could never figure it out, but the arowana and this goldfish were buddies... swimming alongside one another for YEARS!
When my brother moved and the arowana went to live at the LFS, the goldfish went to live in my Dad's koi pond. It lived a great life out there for about 10 years. Actually, the thing may still be alive at my brother's koi pond!
Just remember, arowanas eat alot, are messy and need excellent fitration for optimum health. They need space to turn (wide tank is a good idea). Feed it mostly pellets (from a young age) and some crickets... do your research. Of course, the bigger the tank, the better... but anything about 150+ gallons is ok.
Growing up, as kids, my brother would feed my Dad's arowana frogs, mice, snakes... anything it could fit in its mouth. Of course my Dad didn't know about this...
Last edited by Nomo; 02-02-2011 at 02:11 PM..