The basketball community is rallying around Toronto Raptors player RJ Barrett ... after it was revealed his brother, Nathan, recently passed away.

Nathan's former youth basketball coach, Chris Stewart, confirmed the tragic news on Thursday ... saying the athlete was special to the program.

"Nathan was only with us for a short time in grade 7 before he moved to Florida but whenever he was back in Mississauga the boys connected," Stewart said.

"No parent should ever have to bury a child, hug your kids today a little longer. You will be missed Nathan, RIP ❤️