They are not difficult to keep provided you follow the basic principles.
They are difficult to keep well because most people can't be bothered doing the required work and just put them in with other fish in a large tank and are surprised when they only last a year or less.
High flow rate (massive) Hi oxygen and lower range temp's 75-77 degrees(25c)
They a a fish that dwells in the rapids and need massive water movement.
They require particularly clean water , I mean crystal clean so think 2 x 50% WC's a week , every week ...forever.
They require a large tank (but not as large as a TSN) something like a 6' x 3' x 2.5' would keep a tig for life.
They require careful selection of tankmates they are not agressive and their beautiful trailers can be damaged. I keep them alone.
They require feeding of preferably mixed foods but only every 2nd day.
I use UV's, Chemicals, large 50% WC's every 2nd day and a minimum of 300gal per fish with 10x turnover and I have not lost one yet.