I'm currently pricing a 10Lx4Wx2H tank for my new house but I have also requested a price for one that is 2.5H, if the price difference isn't too much I'll go for the taller tank. My question is, how long would it likely be before a RTC or TSN outgrew this tank? I've always wanted to keep one, especially a RTC and would look to rescue one from a small tank. Say I rescued a 12" fish, how long would I likely have?