I second the specimen tank for atf. I see tons of people who have successful groups for sometimes a year or two, but after a while those atf always either disappear from social media or end up with just one in the tank. This is largely due to the fact that they normally only school as juveniles unless there's some food-related reason for them to gather, like the okavango catfish run. Otherwise, they're quite intolerant not each other (and things they think look like them) once they're mature.
Start with one and have a flawless specimen as opposed to the alternative.