I love gar, but true longnose are unsuitable for all but the biggest tank (8'x4'), as they are fairly inflexible and their nose is easily damaged.
The needle nose gar are actually a livebearer and do best in brackish water (especially if you want to breed them. They are nervous fish that jump or smash against the tanks sides if startled. I had my pair in with archers, belonesox pikes, four-eyes and archers.
I definately agree with rumblesushi, never seen one bigger than 10-12 inches.
