I've had my silver arowana since he was 5" and is now roughly 8" living in a 40b. I wanted to do a pond but my mom doesn't like the idea. As an alternative she recommended a 180g 72" x 24" footprint. I'm just worried he'll outgrow it and it won't be worth the investment. Do you guys think I should invest in the 180g, or keep pushing for the pond?