It is a Gold Severum, a color form of Heros efasciatus, the Common Severum. Seven inches is not bad, relatively few ever reach the maximum size of 10 inches. If he's already more than 3 years old, he is not likely to grow a lot more, maybe another inch or so over several years. Growth slows at sexual maturity, and while most fish continue to grow throughout their lives, other factors can limit how much it grows.
A 70 litre tank is far too small for this species.