Hi and Welcome to the Forum. Agree with Davo here.
If you do want any tankmates, best to introduce them while the Jag is still young, but you would most definitely need a bigger tank, as they won't share a 50 gallon for long and 50's not fit for life for a Jag.
My lfs had a pair of adult Jag's in a 150 which they made look small, but the male got so aggressive killed the female, then he cornered all of the other tankmates (pikes). Last I saw the Jag was 'sharing' the tank with a blackbelt. HTH.