I have a red wolf fish that I got at 3 inches, put him in a planted 29 gallon (30" by 18" by 12") and within 8 months he grew to 7.5" (what he is now) and is incredibly happy, healthy, and active. He eats everything from earthworms to even pellet food. The tank is over-filtered, but I he is getting very big so I'm going to put him in a solo 75 very soon. I would recommend putting him in a larger tank; probably a 40 gallon breeder would be great, and anything larger would likely be overkill, however a based on what I have seen in my own and in other people's wolves a 29 gallon+ for life would be fine as long as it is over-filtered. Best of luck!