Does this sound good for a Black Ghost Knifefish?

I'd like to get a BG, but want to make sure I have every thing down before I take it on. I'm searching for tanks, hoping to get one that is suitable. I don't think it would do too well in a 25 gallon, but what about a 30, 40, or 50? I read from a few "experts" that 50 gallons would due just fine for them. As far as filtration, would a bubble wall and a few bubble stones do okay? I live in Louisiana, and have read that if you live in a warm climate you don't need to worry about heaters. I know they need water temperatures around 70-83 degrees, so do you think I should bother with a heater? Also, would a black light be okay for them, since they are nocturnal? Thanks in advanced!