I keep my arowana in a 125 gallon tank, 6 ft long 3 ft wide and like 2 and a bit ft high
, silver arowana just got him yesterday with a clown knife, arowanas about 4-5", same with the clown knife... They're not too hard to take care of but (when smaller than 3") they are very fragile... I've never heard of green arowanas... If you get one, you can keep it in a smaller tank (such as a 55 gallon) for about a year (if it's less than 6" already) I was told they'll grow to about 1ft or more within a year
anyways, my guys need a bigger tank soon... Anyone think a 240gallon would be good???