I currently have a 3 inch oscar in a 10g with two 10g filters. I got him about 3 months ago when he was only 1.5 inches. he was one of my first fish and i wasnt as informed about aquarium-keeping as i am now. I cant afford a larger tank for him now that i know he grows more than a foot. he's only 3 inches now and doesnt seem cramped in his tank. My family and me love him very much because he is very entertaining. It will be sad when i eventually have to take him back =(. So around what size should he be when i have to take him back? or should i be taking him back now?