tomojsg;5074259; said:what is the minimum requirement to keep 2 6-12" & 2 13-24" aros? and estimated time you can keep them in that size tank until they grow out of it?
Not sure what your asking, do you have 4 arowana and you are keeping them together?
Silver aro grow at about a rate of 1-1.5 inches per month on average. They will keep up this rapid growth rate to around 24-25", Again this is average some may slow at 21-22" and some may grow to 27-28". Once they reach that point their growth will slow to 1-2" per year.
I have 2 silver aro that are nearing 30" they are in a 450g tank and have only been growing a little over an inch per year for the last 3 years or so.