Arowana or Freshwater Stingray, Shovelnose catfish or any type of catfish, Cichlids (by themselves of course), Frontosa's are always neat... I dont know thats just stuff I know people have in their long tanks.
i'd sooner have agressive than non, i don't like boring fish. a freshwater stingray would be nice, but where can i find one cheap? (if there is a such thing as a cheap stingray). and aros get big, wouldn't they get too long to turn around in a 1 foot wide tank?
and my buddy tried pawning off his clown knife to me....that fk'r grew nearly a foot long within a matter of months....and yea i'm pretty sure it'll get way too big for that tank