Just call him Bijoy. We have a wonderful tradition of "official" Bangla nicknames unrelated to the official name, and should use those. Let us be proud of what we are this way, rather than attempting the deplorable "English Medium" hipness we see so often everywhere.
My nickname is Shubho BTW. I'd love to know everyone else's in this forum.
"O people, we created you from the same male and female, and rendered you distinct peoples and tribes, that you may recognize one another. The best among you in the sight of GOD is the most righteous. GOD is Omniscient, Cognizant." (49:13)